#include<iostream>
#include<cstdio>
#include<cmath>
#include<cstring>
#include<algorithm>
#include<queue>
#define ll long long
using namespace std;
const int N=10010,M=200010;
int n,m,s,t,u,v;
ll ans,yu[N],cnt=1,w,h[N],dep[N];
struct qwe{
	int to,net;
}tr[M];
void add(int x,int y,ll z){
	tr[++cnt].to=y;
	yu[cnt]=z;
	tr[cnt].net=h[x];
	h[x]=cnt;
}
bool ff(){
	queue<int> q;
	memset(dep,0,(n+1)*sizeof(int));
	dep[s]=1;
	q.push(s);
	while(!q.empty()){
		int x=q.front();q.pop();
		for(int i=h[x];i;i=tr[i].net){
			int y=tr[i].to;
			if(yu[i]&&!dep[y]){
				dep[y]=dep[x]+1;
				q.push(y);
			}
		}
	}
	return dep[t];
}
ll dfs(int u,ll in){
	if(u==t) return in;
	ll out=0;
	for(int i=h[u];i&&in;i=tr[i].net){
		int v=tr[i].to;
		if(yu[i]&&dep[v]==dep[u]+1){
			ll res=dfs(v,min(in,yu[i]));
			yu[i]-=res;
			yu[i^1]+=res;
			in-=res;
			out+=res;
		}
	}
	if(out==0) dep[u]=0;
	return out;
}
int main(){
	scanf("%d%d%d%d",&n,&m,&s,&t);
	for(int i=1;i<=m;i++){
		scanf("%d%d%lld",&u,&v,&w);
		add(u,v,w);
		add(v,u,0);
	}
	while(ff())
	ans+=dfs(s,1e18);
	printf("%lld\n",ans);
	return 0;
}