#include<bits/stdc++.h>
using namespace std;
#define int long long 
int read()
{
	int x = 0,f = 0;char ch = getchar();
	while(!isdigit(ch)){if(ch=='-')f=1;ch=getchar();}
	while(isdigit(ch)){x=x*10+ch-'0';ch=getchar();}
	return f?-x:x;
}

const int N = 1800100;
struct Dinic{
	int head[N],cur[N],dis[N],s,t,n,cnt;
	struct E{int cap,flow,to,nxt;}e[N];
	void add(int x,int y,int cap)
	{
		e[++cnt].nxt = head[x];
		e[cnt].flow = 0;
		e[cnt].cap = cap;
		e[cnt].to = y;
		head[x] = cnt;
	}
	int Dfs(int x,int a,int t)
	{
		if(x == t || a == 0) return a;
		int f = 0,flow = 0;
		for(int i = cur[x];~i;i = e[i].nxt)
		{
			int y = e[i].to;
			if(dis[x] + 1 == dis[y] && ((f = Dfs(y,min(a,e[i].cap - e[i].flow),t))>0))
			{
				a -= f;
				flow += f;
				e[i].flow += f;
				e[i^1].flow -= f;
				cur[x] = e[i].nxt;
				if(a == 0) break;
 			}
		}
		if(flow == 0) dis[x] = 0;
		return flow;
	}
	bool Bfs(int s,int t)
	{
		queue<int> Q;
		memset(dis,0,sizeof(dis));
		Q.push(s);dis[s] = 1;
		while(Q.size())
		{
			int x = Q.front();Q.pop();
			for(int i = head[x];~i;i = e[i].nxt)
			{
				int y = e[i].to;
				if(e[i].cap > e[i].flow && !dis[y])
				{
					dis[y] = dis[x] + 1;
					Q.push(y);
					if(dis[t])
					{
						return true;
					}
				}
			}	
		}
		return false;
	}
}MaxFlow;
int n,m,s,t;
long long maxflow = 0;
signed main()
{
	n = MaxFlow.n = read();m = read();
	s = MaxFlow.s = read();t = MaxFlow.t = read(),MaxFlow.cnt = -1;
	memset(MaxFlow.head,-1,sizeof(MaxFlow.head));
	for(int i = 1;i <= m;i++)
	{
		int a = read(),b = read(),cap = read();
		MaxFlow.add(a,b,cap);
		MaxFlow.add(b,a,0);
	}
	while(MaxFlow.Bfs(s,t))
	{
		for(int i = 1;i <= MaxFlow.n;i++) MaxFlow.cur[i] = MaxFlow.head[i];
		maxflow += MaxFlow.Dfs(s,0x3f3f3f3f,t);
	}
	cout<<maxflow<<endl;
}