#include <bits/stdc++.h>
using namespace std;
#define ll long long
const int M=100005;
const int N=1005;
int h[N],v[M],w[M],nxt[M];
int mf[N],pre[N];
int idx=1;
void add(int a,int b,int c){
	v[++idx]=b;
	w[idx]=c;
	nxt[idx]=h[a];
	h[a]=idx;
}
int n,m,S,T;
bool bfs(){
	memset(mf,0,sizeof(mf));
	mf[S]=1e9;
	queue<int> q;
	q.push(S);
	while(!q.empty()){
		int u=q.front();
		q.pop();
		for(int i=h[u];i;i=nxt[i]){
			if(!mf[v[i]]&&w[i]){
				mf[v[i]]=min(mf[u],w[i]);
				pre[v[i]]=i;
				q.push(v[i]);
				if(v[i]==T){
					return 1;
				}
				
			}
			
		}
	}
	return 0;
}
ll EK(){
	ll flow=0;
	while(bfs()){
		int tmp=T;
		while(tmp!=S){
			int i=pre[tmp];
			w[i]-=mf[tmp];
			w[i^1]+=mf[tmp];
			tmp=v[i^1];
		}
		flow+=mf[T];
	}
	return flow;
}

int main(){
	cin >> n >> m >> S >> T;
	while(m--){
		int a,b,c;
		cin >> a >> b >> c;
		add(a,b,c);
		add(b,a,0);
	}
	cout << EK() << endl;
}