#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
const int N=200000+10,M=1e4+5,mod=1e9+7;
ll n,m,s,t,h[N],cur[N],cnt=1,vis[N];
struct node{
    ll to,nt,w;
}e[N];
void add(ll u,ll v,ll w)
{
    e[++cnt]={v,h[u],w};
    h[u]=cnt;
}
queue<ll>q;
bool bfs()
{
    memset(vis,0,sizeof(vis));
    vis[s]=1;
    q.push(s);
    while(!q.empty())
    {
        ll u=q.front();
        q.pop();
        cur[u]=h[u];
        for(ll i=h[u];i;i=e[i].nt)
        {
            ll v=e[i].to,w=e[i].w;
            if(w&&!vis[v])
            {
                vis[v]=vis[u]+1;
                q.push(v);
            }
        }
    }
    return vis[t];

}
ll dfs(ll u,ll flow)
{
    if(u==t)
        return flow;
    ll res=flow;
    for(ll i=cur[u];i;i=e[i].nt)
    {
        ll v=e[i].to,w=e[i].w;
        if(w&&vis[u]+1==vis[v])
        {
            ll now=dfs(v,min(res,w));
            if(!now)
                vis[v]=1;
            else
            {
                e[i].w-=now;
                e[i^1].w+=now;
                res-=now;
            }
        }
        if(!res)
        return flow;
    }
    return flow-res;
}
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,u,0);
    }
    ll ans=0;
    while(bfs())
    {
        ans+=dfs(s,0x7fffffff);
    }
    cout<<ans<<endl;
    return 0;
}