#include<iostream>
#include<queue>
#include<cstring>
#define ll long long
#define inf 0x3f3f3f3f
using namespace std;int n,m,s,t;
const int N=210,M=1e4+10;
int h[N],to[M],w[M],ne[M],idx;
int dep[N],now[N];
void add(int a,int b,int c){
	to[++idx]=b;w[idx]=c;ne[idx]=h[a];h[a]=idx;
}
bool bfs(){
	memset(dep,0x3f,sizeof dep);
	queue<int> q;q.push(s);dep[s]=0;now[s]=h[s];
	while(q.size()){
		int tmp=q.front();q.pop();
		for(int i=h[tmp];i;i=ne[i]){
			int j=to[i];
			if(dep[j]==inf&&w[i]>0){
				dep[j]=dep[tmp]+1;
				now[j]=h[j];
				q.push(j);
				if(j==t) return 1;
			}
		}
	}
	return 0;
}
ll dfs(ll u,ll sum){
	//cout<<u<<" ";
	if(u==t) return sum;
	ll flow=0;
	for(int i=now[u];i&&sum>0;i=ne[i]){
		int j=to[i];
		now[u]=i;
		if((dep[j]==dep[u]+1)&&w[i]>0){
			ll k=dfs(j,min(sum,(ll)w[i]));
			if(!k) w[i]=inf;
			w[i]-=k;w[i^1]+=k;
			flow+=k;
			sum-=k;
		}
	}
	return flow;
}
void dinic(){
	ll ans=0;
	while(bfs()) ans+=dfs(s,inf);
	cout<<ans<<endl;
}
int main(){
	cin>>n>>m>>s>>t;
	for(int i=1;i<=m;i++){
		int a,b,c;cin>>a>>b>>c;
		add(a,b,c);add(b,a,0);
	}
	dinic();
	return 0;
}