diff --git a/Codeforces/equalize_prizes b/Codeforces/equalize_prizes
new file mode 100644
index 0000000..6c81308
--- /dev/null
+++ b/Codeforces/equalize_prizes
@@ -0,0 +1,34 @@
+#include <iostream>
+using namespace std;
+ 
+int q;
+int n,k;
+int A[101];
+int minim;
+int ans;
+ 
+int main(){
+    cin >> q;
+ 
+    for(int p = 0; p < q; p++){
+        scanf("%d %d", &n, &k);
+        minim = 1000000000;
+ 
+        for(int i = 0; i < n; i++){
+            scanf("%d",&A[i]);
+            minim = min(minim,A[i]);
+        }
+ 
+        ans = k + minim;
+        for(int i = 0; i < n; i++){
+            if(abs(ans-A[i])>k){
+                ans = -1;
+                break;
+            }
+        }
+ 
+        cout << ans << endl;
+    }
+ 
+    return 0;
+}
diff --git a/Codeforces/exams.cpp b/Codeforces/exams.cpp
new file mode 100644
index 0000000..34b3aa1
--- /dev/null
+++ b/Codeforces/exams.cpp
@@ -0,0 +1,60 @@
+//https://codeforces.com/problemset/problem/479/C
+#include <iostream>
+#include <queue>
+#include <vector>
+#include <algorithm>
+using namespace std;
+
+typedef long long ll;
+typedef pair<unsigned int, unsigned int> puu;
+typedef priority_queue<pair<unsigned int, unsigned int>> pq ;
+
+#define ri(i) scanf("%d",&i)
+#define rl(i) scanf("%ld",&i)
+#define rii(i,j) scanf("%u %u",&i,&j)
+#define FOR(i,a,b) for(int i = a; i <= b; i++)
+#define ROF(i,a,b) for(int i = a; i >= b; i--)
+#define p_arr(A,a,b) FOR(i,a,b){ cout << A[i] << " ";} cout << endl; 
+
+
+
+int N;
+puu A[5001];
+
+int t1,t2;
+pq p;
+
+bool puu_comp(puu p1,puu p2){
+    return p1.first!=p2.first ? p1.first < p2.first : p1.second < p2.second;
+}
+
+
+int exams(int i = N-1){
+    if(i==0){
+        return A[i].second;
+    }
+    if(exams(i-1)<=A[i].second) {return A[i].second;}
+    else {return A[i].first;}
+}
+
+
+int main(){
+
+    ri(N);
+
+    FOR(i,1,N){
+        rii(t1,t2);
+        p.push({t1,t2});
+    }
+
+    ROF(i,N-1,0){
+        A[i] = {p.top().first,p.top().second};
+        p.pop();
+    }
+
+    cout << exams() << endl;
+
+  
+
+    return 0;
+}
diff --git a/Codeforces/printer.cpp b/Codeforces/printer.cpp
new file mode 100644
index 0000000..7f725fe
--- /dev/null
+++ b/Codeforces/printer.cpp
@@ -0,0 +1,106 @@
+#include <iostream>
+#include <queue>
+#include <vector>
+#include <algorithm>
+#include <string>
+using namespace std;
+
+typedef long long ll;
+typedef pair<unsigned int, unsigned int> puu;
+typedef priority_queue<pair<unsigned int, unsigned int>> pq ;
+
+#define ri(i) scanf("%d",&i)
+#define rl(i) scanf("%ld",&i)
+#define rii(i,j) scanf("%d %d",&i,&j)
+#define FOR(i,a,b) for(int i = a; i <= b; i++)
+#define ROF(i,a,b) for(int i = a; i >= b; i--)
+#define p_arr(A,a,b) FOR(i,a,b){ cout << A[i] << " ";} cout << endl; 
+#define MAXINT ~(1<<31)
+
+int n,k;
+string f1;
+string f2;
+
+int f1_rm;
+int f2_rm;
+int f1_lm;
+int f2_lm;
+int candidate;
+
+int f,t;
+
+int ans = MAXINT;
+
+int main(){
+
+        rii(n,k);
+
+    cin >> f2;
+    cin >> f1;
+
+    //find both rm:
+
+    ROF(i,n-1,0){
+        if(f2[i]=='1'){
+            f2_rm = i+1;
+            break;
+        }
+    }
+
+    ROF(i,n-1,0){
+        if(f1[i]=='1'){
+            f1_rm =  i+1;
+            break;
+        }
+    }
+
+    if(f1_rm==0 && f1[0]=='0'){
+        FOR(i,0,n-1){
+            if(f2[i]=='1'){
+                f2_lm =  i+1;
+                break;
+            }            
+        }
+        int mp = (f2_lm+f2_rm)/2;
+        printf("%d\n",max(abs(mp-f2_lm),abs(mp-f2_rm)));
+        printf("%d %d\n", 2, mp);
+        return 0;
+    }
+
+    if(f2_rm==0 && f2[0]=='0'){
+        FOR(i,0,n-1){
+            if(f1[i]=='1'){
+                f1_lm =  i+1;
+                break;
+            }            
+        }
+        int mp = (f1_lm+f1_rm)/2;
+        printf("%d\n",max(abs(mp-f1_lm),abs(mp-f1_rm)));
+        printf("%d %d\n", 1, mp);
+        return 0;
+    }
+
+
+    FOR(i,1,n){
+        ans = min(ans,max(abs(i-f2_rm),i+k+f1_rm));
+        ans = min(ans,max(abs(i-f1_rm),i+k+f2_rm));
+    }
+
+    FOR(i,1,n){
+        if(ans==max(abs(i-f2_rm),i+k+f1_rm)){
+            printf("%d\n",ans);
+            printf("%d %d\n",2,i);
+            return 0;
+        }
+        if(ans==max(abs(i-f1_rm),i+k+f2_rm)){
+            printf("%d\n",ans);
+            printf("%d %d\n",1,i);
+            return 0;
+        }
+    }
+
+    //cout << ans << endl;
+    return 0;
+}
+
+ 
diff --git a/Codeforces/yellow_cards_cf.cpp b/Codeforces/yellow_cards_cf.cpp
new file mode 100644
index 0000000..3e78493
--- /dev/null
+++ b/Codeforces/yellow_cards_cf.cpp
@@ -0,0 +1,80 @@
+#include <iostream>
+#include <queue>
+#include <vector>
+#include <algorithm>
+using namespace std;
+
+typedef long long ll;
+typedef pair<unsigned int, unsigned int> puu;
+typedef priority_queue<pair<unsigned int, unsigned int>> pq ;
+
+#define ri(i) scanf("%d",&i)
+#define rl(i) scanf("%ld",&i)
+#define rii(i,j) scanf("%i %i",&i,&j)
+#define FOR(i,a,b) for(int i = a; i <= b; i++)
+#define ROF(i,a,b) for(int i = a; i >= b; i--)
+#define p_arr(A,a,b) FOR(i,a,b){ cout << A[i] << " ";} cout << endl; 
+
+int A1,A2;
+int K1,K2;
+int n;
+
+int min_k,max_k;
+int min_a,max_a;
+
+int mini,maxi;
+
+int mini_1[1000];
+int mini_2[1000];
+
+int maxi_1[1000];
+int maxi_2[1000];
+
+int main(){
+
+    ri(A1);
+    ri(A2);
+    ri(K1);
+    ri(K2);
+    ri(n);
+
+    if(K1>K2){
+        max_k = K1;
+        max_a = A1;
+        min_k = K2;
+        min_a = A2;
+    }
+    else{
+        max_k = K2;
+        max_a = A2;
+        min_k = K1;
+        min_a = A1;
+    }
+
+    //compute max:
+    int temp_n = n;
+    int temp_maxi = n/min_k;
+
+    if(temp_maxi > min_a){
+        temp_maxi = min_a;
+        temp_n -= min_a*min_k;
+
+        temp_maxi += temp_n/max_k;
+    }
+    maxi = temp_maxi;
+
+    //compute mini:
+    temp_n = n;
+    if((min_k-1)*min_a + (max_k-1)*max_a >= n){
+        mini = 0;
+    }
+    else{
+        mini = n - ((min_k-1)*min_a + (max_k-1)*max_a);
+    }
+
+    printf("%d %d\n",mini,maxi);
+
+    return 0;
+}
+
+ 
diff --git a/SPOJ/ARBITRAG.cpp b/SPOJ/ARBITRAG.cpp
new file mode 100644
index 0000000..b242c79
--- /dev/null
+++ b/SPOJ/ARBITRAG.cpp
@@ -0,0 +1,108 @@
+#include <iostream>
+#include <list>
+#include <vector>
+#include <map>
+ 
+using namespace std;
+ 
+struct edge {int a,b; float c;};
+ 
+const int MAXINT = ~(1<<31);
+ 
+int N;
+int M;
+int n_case = 1;
+float len;
+ 
+vector<pair<float,int>> graph[31];
+list<edge> E;
+map<string,int> names;
+char c1[200];
+char c2[200];
+ 
+bool bellman(int start){
+ 
+    float cost[31];
+    float maxf = (float) MAXINT;
+    for(int i = 0; i < N; i++){
+        cost[i] = maxf;
+    }
+ 
+    cost[start] = -1.0f;
+ 
+    for(int l = 1; l < N; l++ ){
+        for(edge e:E){
+ 
+            if(cost[e.a]==maxf &&cost[e.b]==maxf){continue;}
+ 
+            if(cost[e.b] > cost[e.a]*e.c){
+                cost[e.b] = cost[e.a]*e.c;
+            }
+ 
+        }
+    }
+ 
+    for(edge e:E){
+ 
+        if(cost[e.a]==maxf &&cost[e.b]==maxf){continue;}
+ 
+        if(cost[e.b] > cost[e.a]*e.c){
+ 
+            return true; // there's infinite loop
+            
+        }
+ 
+    }
+    return false; //no infinite loop
+ 
+}
+ 
+bool arbitrag(){
+ 
+    for(int i = 0; i < N; i++){
+        if(bellman(i)){return true;}
+    }
+ 
+    return false;
+}
+ 
+ 
+int main(){
+ 
+    scanf("%d",&N);
+    int temp1;
+    int temp2;
+    while(N!=0){
+ 
+        for( int i = 0; i < N; i++){
+            cin >> c1;
+            names[c1] = i;
+        }
+ 
+        scanf("%d", &M);
+ 
+        for(int j = 0; j < M; j++){
+            scanf("%s %f %s",c1,&len,c2);
+            temp1 = names[c1];
+            temp2 = names[c2];
+ 
+            graph[temp1].push_back({len,temp2});
+ 
+            E.push_back({temp1,temp2,len});
+        }
+ 
+        printf("Case %d: %s \n",n_case,arbitrag() ? "Yes" : "No");
+ 
+ 
+ 
+        scanf("%d",&N);
+        n_case++;
+        names.clear();
+        for(int i = 0; i < N; i++){
+            graph[i].clear();
+        }
+        E.clear();
+    }
+ 
+    return 0;
+} 
diff --git a/SPOJ/CANDN.cpp b/SPOJ/CANDN.cpp
new file mode 100644
index 0000000..fdbc975
--- /dev/null
+++ b/SPOJ/CANDN.cpp
@@ -0,0 +1,98 @@
+#include <iostream>
+#include <vector>
+#include <queue>
+ 
+using namespace std;
+ 
+int J,B,C,N,S;
+int e1,e2,l;
+ 
+int ans,ansN,ansC;
+const int MAXINT = ~(1<<31);
+int memo_charly[5001];
+int memo_nito[5001];
+int memo_bar[5001];
+ 
+ 
+void dijkstra(int (&memo)[5001],int i, vector<pair<int,int>> (graph)[]){
+    
+    priority_queue<pair<int,int>> q;
+    int temp_w,temp_node;
+    pair<int,int> temp_e;
+ 
+    memo[i] = 0;
+    q.push({0,i});
+ 
+    while(!q.empty()){
+        temp_w = -q.top().first;
+        temp_node = q.top().second;
+ 
+        for(int j = 0; j < graph[temp_node].size(); j++){
+            temp_e = graph[temp_node][j];
+            if(temp_w + temp_e.first < memo[temp_e.second]){
+                memo[temp_e.second] = temp_w + temp_e.first;
+                q.push({-memo[temp_e.second],temp_e.second});
+            }
+        }
+ 
+        q.pop();
+    }
+    
+}
+ 
+void init_memo(int (&memo)[5001]){
+    for(int i = 1; i <= J; i++){
+        memo[i] = MAXINT;
+    }
+}
+ 
+void candn(vector<pair<int,int>> (graph)[5001]){
+    //init memos:
+    init_memo(memo_nito);
+    init_memo(memo_charly);
+    init_memo(memo_bar);
+ 
+    //dijkstra over the three memos:
+    dijkstra(memo_nito,N,graph);
+    dijkstra(memo_charly,C,graph);
+    dijkstra(memo_bar,B,graph);
+ 
+    int maxi = -1;
+    int maxi_node = -1;
+    int min_cost_charly = memo_bar[C];
+    int min_cost_nito = memo_bar[N];
+ 
+    for(int i = 1; i <= J; i++){
+        if((memo_bar[i] + memo_charly[i]) == min_cost_charly && (memo_bar[i] + memo_nito[i])==min_cost_nito && memo_bar[i]>maxi){
+            maxi = memo_bar[i];
+            maxi_node = i;
+        }
+    }
+ 
+    ans = maxi;
+    ansC = memo_charly[maxi_node];
+    ansN = memo_nito[maxi_node];
+ 
+}
+ 
+int main(){
+ 
+    scanf("%d %d %d %d %d",&J,&B,&C,&N,&S);
+    while(J!=-1){
+        vector<pair<int,int>> graph[5001];
+ 
+        for(int i = 0; i < S; i++){
+            scanf("%d %d %d",&e1,&e2,&l);
+            graph[e1].push_back({l,e2});
+            graph[e2].push_back({l,e1});
+        }
+ 
+        candn(graph);
+ 
+        cout << ans << " " << ansC << " " << ansN << endl; 
+ 
+        scanf("%d %d %d %d %d",&J,&B,&C,&N,&S);
+    }
+ 
+    return 0;
+}
diff --git a/SPOJ/mixtures.cpp b/SPOJ/mixtures.cpp
new file mode 100644
index 0000000..c89d00f
--- /dev/null
+++ b/SPOJ/mixtures.cpp
@@ -0,0 +1,92 @@
+#include <iostream>
+using namespace std;
+ 
+int n;
+int mixes[101];
+int MAXINT = ~(1<<31);
+int T[101];
+int memo[101][101];
+int counter;
+int get_sum(int b, int e){
+ 
+    if(e<b){ return 0; }
+ 
+    int begin = max(b,0);
+    int end = min(e,n-1);
+ 
+    if(begin==0){return T[end]%100;}
+ 
+    return (T[end] - T[begin - 1])%100;
+ 
+}
+ 
+ 
+ 
+ 
+int mixtv2(int i = 0, int j = n-1){
+    //i: inicio
+    //j: fin
+    int mini = MAXINT;
+    int temp;
+    int left;
+    int right;
+ 
+    counter++;
+ 
+    if(j==i){
+        return 0;
+    }
+ 
+    if( j - i + 1 == 2){
+        return mixes[i]*mixes[j];
+    }
+ 
+    for(int k = i; k < j ; k++){
+        
+        if(memo[i][k]==-1){
+            memo[i][k] = mixtv2(i,k);
+        }
+        if(memo[k+1][j]==-1){
+            memo[k+1][j] = mixtv2(k+1,j);
+        }
+ 
+        left = memo[i][k];
+        right = memo[k+1][j];
+ 
+        temp = left + right + get_sum(i,k)*get_sum(k+1,j);
+        
+ 
+        mini = min(mini,temp);
+    }
+ 
+    return mini;
+}
+ 
+ 
+ 
+int main(){
+ 
+    while(scanf("%d", &n)>0){
+ 
+        //initialize memo:
+        for(int i = 0; i < n; i++){
+            for(int j = 0; j < n; j++){
+                memo[i][j] = -1;
+            }
+        }
+ 
+        for(int i = 0; i < n; i++){
+            cin >> mixes[i];
+            T[i] = 0;
+        }
+ 
+        T[0] = mixes[0];
+        for(int i = 1; i < n; i++){
+            T[i] = T[i-1] + mixes[i];
+        }
+ 
+        cout << mixtv2() << endl;
+    }
+ 
+    return 0;
+} 
diff --git a/SPOJ/soldier.cpp b/SPOJ/soldier.cpp
new file mode 100644
index 0000000..0e6dd6b
--- /dev/null
+++ b/SPOJ/soldier.cpp
@@ -0,0 +1,84 @@
+#include <iostream>
+#include <vector>
+using namespace std;
+ 
+int N,T;
+int price[110];
+int quality[110];  
+vector<int> equipment[7];
+int t,p,q;
+int code[7] = {-1, 2,3,5,7,11,13};
+int ans;
+int availableTypes = 1;
+int counter;
+int memo[7][1010];
+int soldierv2(int i = 6, int money = T){
+    counter ++;
+ 
+    int ans = -1;
+    int temp1;
+    if(money <= 0){
+        return -1;
+    }
+    if(i==1){
+        for(int j = 0; j < equipment[i].size(); j++){
+            ans = money - price[equipment[i].at(j)] >= 0 ? max(ans,quality[equipment[i].at(j)]) : ans;
+        }
+        return ans;
+    }
+ 
+    for(int j = 0; j < equipment[i].size(); j++){
+ 
+ 
+        if(memo[i-1][money - price[equipment[i].at(j)]]==0){
+            temp1 = soldierv2(i-1,money - price[equipment[i].at(j)]);
+            memo[i-1][money - price[equipment[i].at(j)]] = temp1;
+        }
+        else{
+            temp1 = memo[i-1][money - price[equipment[i].at(j)]];
+        }
+        temp1 = min(quality[equipment[i].at(j)],temp1);
+        ans = temp1 != -1? max(temp1,ans) : ans;
+    }
+ 
+    return ans;
+}
+ 
+ 
+int main(){
+    for(int i = 1; i <= 6; i++ ){
+        equipment[i].reserve(1000);
+    }
+ 
+    scanf("%d %d", &N, &T);
+ 
+    for(int i = 1; i <= N; i++){
+        scanf("%d %d %d", &t, &p, &q);
+ 
+        if(t<=6){
+            price[i] = p;
+            quality[i] = q;
+            equipment[t].push_back(i);
+            if(availableTypes%code[t]!=0){
+                availableTypes *= code[t];
+            }
+        }
+    }
+ 
+    if(availableTypes!=30030){
+        cout << 0 << endl;
+    }
+    else{
+        ans = soldierv2();
+        if(ans==-1){
+            cout << 0 << endl;
+        }
+        else{
+            cout << ans << endl;
+ 
+        }
+ 
+    }
+    
+    return 0;
+}