#include<bits/stdc++.h>
using namespace std;
const int N=1e3+5,M=1e6+5;
int n,m,s,t,vis[N][N],V[N],pre[N];
long long dis[N],ans;
queue <int> q;
struct Edge{
    int next,to;
	long long c;
} edge[M];
int head[M],sumedge=1;
void build_edge(int from,int to,int c) {
	sumedge++;
    edge[sumedge].next=head[from];
    edge[sumedge].to=to;
    edge[sumedge].c=c;
    head[from]=sumedge;
    return;
}
bool check() {
	while(!q.empty()) q.pop();
	memset(V,0,sizeof(V));
	q.push(s),V[s]=true,dis[s]=INT_MAX;
	while(!q.empty()) {
		int u=q.front();q.pop();
		for(int i=head[u];i;i=edge[i].next) {
			if(edge[i].c) {
				int v=edge[i].to;
				if(V[v]) continue;
				dis[v]=min(dis[u],edge[i].c),pre[v]=u;
				q.push(v),V[v]=true;
				if(v==t) return true;
			}
		}
	}
	return false;
}
void update() {
	int u=t;
	while(u!=s) {
		int v=pre[u];
		edge[v].c-=dis[t],edge[v^1].c+=dis[t];
		u=edge[v^1].to;
	}
	ans+=dis[t];
    return;
}
int main() {
	int u,v,w;
	cin>>n>>m>>s>>t;
	for(int i=1;i<=m;i++) {
		cin>>u>>v>>w;
		if(!vis[u][v]) {
			vis[u][v]=sumedge+1;
			build_edge(u,v,w),build_edge(v,u,0);
		}
		else edge[vis[u][v]].c+=w;
	}
	while(check()) update();
	cout<<ans;
	return 0;
}