#include<bits/stdc++.h>
# define ll long long
using namespace std;
const int N = 1e4,inf = 1023021618;
int n,t,m,s;
struct edge{
	int u,v,nxt;
	ll w;
}e[N];
int tot=-1;
int h[N],cur[N];
ll maxflorr;
int d[N];
inline void add(int u,int v,int w){
	//正 
	e[++tot].u = u;
	e[tot].v = v;
	e[tot].w = w;
	e[tot].nxt = h[u];
	h[u] = tot;
	//反
	e[++tot].u = v;
	e[tot].v = u;
	e[tot].w = 0;
	e[tot].nxt = h[v];
	h[v] = tot; 
}
inline bool bfs(){
	for(int i = 1;i <= n;i ++)d[i] = -1;
	queue<int>q;
	q.push(s);
//	cur[s] = h[s];
	d[s] = 0;
	while(!q.empty()){
		int u = q.front();
		q.pop();
		for(int i = h[u];i>-1;i = e[i].nxt){
			int v = e[i].v;
			if(e[i].w > 0 && d[v] == -1){
				q.push(v);
				d[v] = d[u] + 1;
				//cur[v] = h[v];
				if(v == t)return 1;
			}
		}
	}
	return 0;
}
inline ll dfs(int u,ll flow){
	if(u == t||flow==0)return flow;
	ll f,res = 0;
	for(int i = cur[u];i!=-1;i = e[i].nxt){
		cur[u] = i;
		int v = e[i].v;
		if( d[v] == d[u] + 1 && (f = dfs(v,min(flow,e[i].w)))){
			e[i].w -= f;
			e[i^1].w += f;
			res += f;
			flow -= f;
			if(flow==0)return res;
		}
	}
	return res;
}
int main(){
	cin.tie(0);
	cout.tie(0);
	cin >> n >> m >> s >> t;
	for(int i = 1;i <= m;i ++){
		int u,v,w;
		cin >> u >> v >> w;
		add(u,v,w);
	}
	while(bfs()){
		for(int i = 1;i <= n;i ++)cur[i] = h[i];
		maxflorr += dfs(s,inf);
	}
	cout << maxflorr << endl;
	return 0;
}