#include<algorithm>
#include<cmath>
#include<cstring>
#include<iostream>
#include<ctime>
#include<map>
#include<queue>
#include<cstdlib>
#include<string>
#include<climits>
#include<set>
#include<vector>
using namespace std;
const int maxN=1000005,maxM=1000005,oo=10000000000000000ll;
int n,m,s,t,cnt,Head[maxN],Next[maxM],W[maxM],V[maxM],Depth[maxN],cur[maxN];
void _Add(int u,int v,int w){
    cnt++;
    Next[cnt]=Head[u];
    Head[u]=cnt;
    V[cnt]=v;
    W[cnt]=w;
}
void Add_Edge(int u,int v,int w){
    _Add(u,v,w);
    _Add(v,u,0);
}
int dfs(int u,int flow){
    if(u==t){
        return flow;
    }
    for(int& i=cur[u];i!=-1;i=Next[i]){
        if((Depth[V[i]]==Depth[u]+1)&&(W[i]!=0)){
            int di=dfs(V[i],min(flow,W[i]));
            if(di>0){
                W[i]-=di;
                W[i^1]+=di;
                return di;
            }
        }
    }
    return 0;
}
int bfs(){
    queue<int> Q;
    while(!Q.empty()){
        Q.pop();
    }
    memset(Depth,0,sizeof(Depth));
    Depth[s]=1;
    Q.push(s);
    do{
        int u=Q.front();
        Q.pop();
        for(int i=Head[u];i!=-1;i=Next[i]){
            if((Depth[V[i]]==0)&&(W[i]>0)){
                Depth[V[i]]=Depth[u]+1;
                Q.push(V[i]);
            }
        }
    }
    while(!Q.empty());
    if(Depth[t]>0){
        return 1;
    }
    return 0;
}
int Dinic(){
    int Ans=0;
    while (bfs()){
        for(int i=1;i<=n;i++){
            cur[i]=Head[i];
        }
        while(int d=dfs(s,oo)){
            Ans+=d;
        }
    }
    return Ans;
}
int main(){
    int u,v,w;
    cnt=-1;
    memset(Head,-1,sizeof(Head));
    memset(Next,-1,sizeof(Next));
    scanf("%d%d%d%d",&n,&m,&s,&t);
    for(int i=1;i<=m;i++){
        scanf("%d%d%d",&u,&v,&w);
        Add_Edge(u,v,w);
    }
    printf("%d\n",Dinic());
    return 0;
}