#include <bits/stdc++.h>
#define int long long
#define inf 0x7f7f7f7f
using namespace std;
class Edge
{
public:
	int u,v,w,next;
}e[100001];
queue<int> r;
int elast[201],cur[201],level[201],cnt[201],n,s,t,link(1),ans;
void add(int u,int v,int w)
{
	e[++link]=(Edge){u,v,w,elast[u]};
	elast[u]=link;
}
void bfs(int u)
{
	memset(level,inf,sizeof(level));
	cnt[level[u]=0]=1;
	r.push(u);
	int v,i;
	while(!r.empty())
	{
		u=r.front(),r.pop();
		for(i=elast[u];i!=0;i=e[i].next)
		{
			v=e[i].v;
			if (level[v]>=inf)
			{
				cnt[level[v]=level[u]+1]++;
				r.push(v);
			}
		}
	}
}
int augment(int u,int flow)
{
	int v,k(0),temp,i;
	if (u==t) return flow;
	for(i=cur[u];i!=0;i=e[i].next)
	{
		cur[u]=i;
		v=e[i].v;
		if (e[i].w>0 && level[u]==level[v]+1)
		{
			temp=augment(v,min(flow-k,e[i].w));
			e[i].w-=temp,e[i^1].w+=temp;
			k+=temp;
			if (k==flow || level[s]>t)
				return k;
		}
	}
	if (level[s]>t) return k;
	cnt[level[u]]--;
	if (!cnt[level[u]]) level[s]=t+1;
	cnt[++level[u]]++;
	cur[u]=elast[u];
	return k;
}
signed main()
{
	//¡¾Ä£°å¡¿ÍøÂç×î´óÁ÷
	int m,u,v,w;
	scanf("%lld%lld%lld%lld",&n,&m,&s,&t);
	while(m--)
	{
		scanf("%lld%lld%lld",&u,&v,&w);
		add(u,v,w);
		add(v,u,0);
	}
	bfs(t);
	while(level[s]<=t)
	{
		memcpy(cur,elast,sizeof(cur));
		ans+=augment(s,inf);
	}
	printf("%lld",ans);
}