#include<bits/stdc++.h>
typedef long long LL;
using namespace std;
const int N=210,M=5010;
const LL inf=1e18;
int n,m,s,t,u,v;
int tot=1,head[N],ver[M*2],nxt[M*2],flag[N][N];
int pre[N];
LL edge[M*2],minv[N],w,ans;
bool vis[N];
void addedge(int x,int y,LL z) {
	ver[++tot]=y;
	edge[tot]=z;
	nxt[tot]=head[x];
	head[x]=tot;
}
bool bfs() {
	memset(vis,0,sizeof(vis));
	queue<int> q;
	q.push(s); vis[s]=1; minv[s]=inf;
	for(; q.size(); ) {
		int x=q.front(); q.pop();
		for(int i=head[x]; i; i=nxt[i]) {
			if(edge[i]==0) continue;
			int y=ver[i];
			if(vis[y]) continue;
			minv[y]=min(minv[y],edge[i]);
			pre[y]=i; q.push(y); vis[y]=1;
			if(y==t) return 1;
		}
	}
	return 0;
}
void update() {
	int x=t;
	for(; x!=s; ) {
		int v=pre[x];
		edge[v]-=minv[t];
		edge[v^1]+=minv[t];
		x=ver[v^1];
	}
	ans+=minv[t];
}
int main() {
	cin>>n>>m>>s>>t;
	for(int i=1; i<=m; i++) {
		cin>>u>>v>>w;
		if(flag[u][v]==0) {
			addedge(u,v,w);
			flag[u][v]=tot;
			addedge(v,u,0);
		} else {
			edge[flag[u][v]]+=w;
		}
	}
	for(; bfs(); ) {
		update();
	}
	cout<<ans<<endl;
	return 0;
}