#include<bits/stdc++.h>
#define maxn 1005
using namespace std;
int n,m,s,t,f[maxn][maxn],dd[maxn],trc[maxn],c[maxn][maxn],res;
vector<int> e[maxn];
void findgraph()
{
    queue<int> q;
    while(!q.empty()) q.pop();
    dd[s]=1;
    q.push(s);
    while(!q.empty())
    {
        int u=q.front();
        q.pop();
        for (int i=0;i<(int)e[u].size();i++)
        {
            int v=e[u][i];
            if (dd[v]) continue;
            if (f[u][v]>=c[u][v]) continue;
            trc[v]=u;
            dd[v]=1;;
            if (v==t)
            {
                return;
            }
            q.push(v);
        }
    }
}
void incflow()
{
    int tmp=1000000000;
    int v=t;
    while(v!=s)
    {
        int u=trc[v];
        tmp=min(tmp,c[u][v]-f[u][v]);
        v=u;
    }
    v=t;
    while(v!=s)
    {
        int u=trc[v];
        f[u][v]+=tmp;
        f[v][u]-=tmp;
        v=u;
    }
    res+=tmp;
}
int main()
{
    //freopen("NKFLOW.inp","r",stdin);
    ios::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);
    cin>>n>>m>>s>>t;
    for (int i=1;i<=m;i++)
    {
        int u,v,val;
        cin>>u>>v>>val;
        c[u][v]=val;
        e[u].push_back(v);
        e[v].push_back(u);
    }
    while(1)
    {
        memset(dd,0,sizeof(dd));
        memset(trc,0,sizeof(trc));
        findgraph();
        if (trc[t]==0) break;
        incflow();
    }
    cout<<res;
    return 0;
}