#include <iostream>
#include <fstream>
#include <vector>
#include <queue>
#define NMAX 1001
#define oo 0x3f3f
using namespace std;
int n,m,F[NMAX][NMAX],C[NMAX][NMAX],flux,s,d,x,y,r;
int T[NMAX],q[NMAX];
ifstream f("maxflow.in");
ofstream g("maxflow.out");
int BF()
{
    int i,k,p,u;
    p=u=0;
    for(i=1;i<=n;i++)
        T[i]=0;
    q[0]=s;
    T[s]=-1;
    for(;p<=u;p++)
    {
        k=q[p];
        for(i=1;i<=n;i++)
            if(!T[i]&&C[k][i]>F[k][i])
            {
                q[++u]=i;
                T[i]=k;
                if(i==d)return 1;
            }
    }
    return 0;
}
int main()
{
    f>>n>>m>>s>>d;
    for(int i=1;i<=m;i++)
    {
        f>>x>>y;
        f>>C[x][y];
    }
    int i;
    for(;BF();flux+=r)
    {
        r=oo;
        for(i=d;i!=s;i=T[i])
            r=min(r,C[T[i]][i]-F[T[i]][i]);
        for(i=d;i!=s;i=T[i])
            F[T[i]][i]+=r;
    }
    g<<flux;
    return 0;
}