#include<bits/stdc++.h>
using namespace std;
const int N=205,M=5e3+5;
const long long INF=1e18+5;
long long d[N],delta,ans;
int n,m,s,t,k=1,head[N],cur[N];
queue<int>q;
struct node{
	int v,next;
	long long w;
}edge[M];
inline void addedge(int from,int to,int w){
	edge[++k].next=head[from];
	edge[k].v=to;
	edge[k].w=w;
	head[from]=k;
}
inline int bfs(){
	while(!q.empty())	q.pop();
	memset(d,0,sizeof(d));
	d[s]=1;
	q.push(s);
	while(!q.empty()){
		int u=q.front();
		q.pop();
		for(int i=head[u];i;i=edge[i].next){
			int v=edge[i].v,w=edge[i].w;
			if(d[v])	continue;
			if(w)	d[v]=d[u]+1,q.push(v); 
		}	
	}
	return d[t];
}
inline long long dfs(int u,long long flow){
	if(u==t)	return flow;
	long long res=0;
	for(int &i=cur[u];i&&flow;i=edge[i].next){
		long long v=edge[i].v,&w=edge[i].w;
		if(d[v]==d[u]+1&&w){
			long long de=dfs(v,min(flow,w));
			if(!de)	d[v]=INF;
			w-=de,edge[i^1].w+=de,res+=de,flow-=de;
		}
	}
	if(!res)	d[u]=0;
	return res;
}
inline void dinic(){
	while(bfs()){
		for(int i=1;i<=n;i++)	cur[i]=head[i];
		while(delta=dfs(s,INF))	ans+=delta;
	}
} 
inline int read(){
	int a=0;
	char c=getchar();
	while(c<'0'||c>'9')	c=getchar();
	while(c>='0'&&c<='9')	a=a*10+c-'0',c=getchar();
	return a;
}
int main(){
	memset(head,0,sizeof(head));
	n=read(),m=read(),s=read(),t=read();
	for(int i=1;i<=m;i++){
		int x,y,z;
		x=read(),y=read(),z=read(); 
		addedge(x,y,z);
		addedge(y,x,0);
	}
	dinic();
	printf("%lld",ans);
	return 0;
}