#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
const int maxn=1e7+10;
const ll INF=0xffffffff;
ll n,m,s,t;
struct node
{
	ll v;
	ll val;
	ll nextv;
};
struct node2
{
	int before;
	int b;
};
node c[maxn];
ll vis[maxn]={};
ll hd[maxn];
ll k=1;
node2 p[maxn]={};
void add(ll ur,ll vr,ll valr)
{
	k++;
	c[k].v=vr;
	c[k].val=valr;
	c[k].nextv=hd[ur];
	hd[ur]=k;
}
bool bfs()
{
	memset(p,-1,sizeof(p));
	memset(vis,0,sizeof(vis));
	queue<int>q;
	vis[s]=1;
	q.push(s);
	while(!q.empty())
	{
		ll r=q.front();
		for(ll i=hd[r];i!=0;i=c[i].nextv)
		{
			ll h=c[i].v;
			if(vis[h]==0&&c[i].val!=0)
			{
				p[h].before=r;
				p[h].b=i;
				if(h==t)
					return true;
				vis[h]=1;
				q.push(h);
			} 
		}
		q.pop();
	}
	return false;
}
ll EK()
{
	ll ans=0;
	while(bfs())
	{
		ll mn=INF;
		for(int i=t;i!=s;i=p[i].before)
		{
			mn=min(mn,c[p[i].b].val);
		}
		for(int i=t;i!=s;i=p[i].before)
		{
			c[p[i].b].val=c[p[i].b].val-mn;
			c[p[i].b^1].val=c[p[i].b^1].val+mn;
		}
		ans+=mn;
	}
	return ans;
}
int main()
{
	cin>>n>>m>>s>>t;
	for(int i=1;i<=m;i++)
	{
		ll u,v,w;
		cin>>u>>v>>w;
		add(u,v,w);
		add(v,w,0);
	}
	cout<<EK();
	return 0;
}