#include <bits/stdc++.h>
using namespace std;
using ll = long long;
#include <atcoder/maxflow>

int main() {
    int n, m, s, t;
    cin >> n >> m >> s >> t;
    --s, --t;
    atcoder::mf_graph<ll> mf(n);
    for (int i = 0; i < m; ++i) {
        int u, v;
        ll c;
        cin >> u >> v >> c;
        --u, --v;
        mf.add_edge(u, v, c);
    }
    ll ans = mf.flow(s, t);
    cout << ans << endl;
}