#include<bits/stdc++.h>
#include<atcoder/maxflow>
using namespace std;

int main(){
  int n,m,s,t;
  cin>>n>>m>>s>>t;
  s--;t--;
  atcoder::mf_graph<long long> g(n);
  for (int i=0;i<m;i++){
    int u,v,c;
    cin>>u>>v>>c;
    u--;v--;
    g.add_edge(u,v,c);
  }
  cout<<g.flow(s,t)<<endl;
}