#include <iostream>
#include <queue>
#include <cstring>
using namespace std;
typedef long long ll;
const int N=207, M=5007;
int n, m, s, t;
int head[N], to[M<<1], nxt[M<<1], tot=1, now[N];
ll val[M<<1], dis[N];
ll ans=0;
queue<int> q;
void add(int u, int v, ll w){
	tot++;
	nxt[tot]=head[u];
	head[u]=tot;
	to[tot]=v;
	val[tot]=w;
}
int bfs(){
	memset(dis, 0x3f, sizeof(dis));
	while(q.size())
		q.pop();
	q.push(s);
	dis[s]=0;
	now[s]=head[s];
	while(q.size()){
		int u=q.front();q.pop();
		for(int i=head[u];i;i=nxt[i]){
			int v=to[i];
			if(val[i]>0 && dis[v]==0x3f3f3f3f3f3f3f3f){
				q.push(v);
				now[v]=head[v];
				dis[v]=dis[u]+1;
				if(v==t)
					return 1;
			}
		}
	}
	return 0;
}
int dfs(int x, ll flow){
	if(x==t || !flow)
		return flow;
	ll ans=0;
	for(int i=now[x];i && flow;i=nxt[i]){
		now[x]=i;
		int v=to[i];
		if(val[i]>0 && dis[v]==dis[x]+1){
			ll f=dfs(v, min(flow, val[i]));
			if(f==0)
				dis[v]=0x3f3f3f3f3f3f3f3f;
			val[i]-=f;
			val[i^1]+=f;
			ans+=f;
			flow-=f;
		}
	}
	return ans;
}
int main(){
	cin>>n>>m>>s>>t;
	for(int i=1;i<=m;i++){
		int u, v;
		ll w;
		cin>>u>>v>>w;
		add(u, v, w);add(v, u, w);
	}
	while(bfs()) ans+=dfs(s, 0x3f3f3f3f3f3f3f3fLL);
	cout<<ans<<endl;
	return 0;
}

AC#9 #11 #12 其他WA