#include <bits/stdc++.h>

using namespace std;
using ll = long long ;
const ll N=100010;
const ll M=200010;

ll h[N],ne[M],e[M],f[M],d[N],cur[M],idx,n,m,S,T;
const ll inf=LONG_LONG_MAX;

void add(ll u,ll v,ll w){
    e[idx]=v,ne[idx]=h[u],f[idx]=w,h[u]=idx++;
    e[idx]=u,ne[idx]=h[v],f[idx]=0,h[v]=idx++;
}

bool bfs(){
    queue <ll> q;
    q.push(S);
    memset(d,-1,sizeof d);
    cur[S]=h[S];
    d[S]=0;
    while(q.size()){
        auto t=q.front();
        q.pop();
        for(int i=h[t];i!=-1;i=ne[i]){
            int ver=e[i];
            if(d[ver]==-1 && f[i]) {
                d[ver] = d[t] + 1;
                cur[ver] = h[ver];
                if (ver == T) return true;
                q.push(ver);
            }
        }
    }
    return false;
}

int find(ll u,ll limit){
    if(u==T) return limit;
    ll flow=0;
    for(int i=cur[u];i!=-1 && flow<limit;i=ne[i]){
        cur[u]=i;
        int ver=e[i];
        if(d[ver]==d[u]+1 && f[i]){
            int t=find(ver,min(f[i],limit-flow));
            if(t==0) d[ver]=-1;
            f[i]-=t,f[i^1]+=t,flow+=t;
        }
    }
    return flow;
}

int main(){
    cin>>n>>m>>S>>T;
    memset(h,-1,sizeof h);
    for(ll i=1;i<=m;i++){
        ll u,v,w;
        cin>>u>>v>>w;
        add(u,v,w);
    }
    ll ans=0,flow;
    while(bfs())while(flow = find(S,inf)) ans+=flow;
    cout<<ans<<endl;
    return 0;
}