#include <bits/stdc++.h>
using namespace std;

struct Edge {
    int v, rev;
    long long cap;
};

vector<vector<Edge>> adj;

void add_edge(int u, int v, long long c) {
    adj[u].push_back({v, (int)adj[v].size(), c});
    adj[v].push_back({u, (int)adj[u].size() - 1, 0});
}

long long edmonds_karp(int s, int t, int n) {
    long long flow = 0;
    while (true) {
        vector<int> parent(n + 1, -1);
        vector<int> parent_edge(n + 1, -1);
        queue<int> q;
        q.push(s);
        parent[s] = s;
        while (!q.empty() && parent[t] == -1) {
            int u = q.front(); q.pop();
            for (int i = 0; i < (int)adj[u].size(); i++) {
                auto &e = adj[u][i];
                if (parent[e.v] == -1 && e.cap > 0) {
                    parent[e.v] = u;
                    parent_edge[e.v] = i;
                    q.push(e.v);
                }
            }
        }
        if (parent[t] == -1) break;
        long long inc = LLONG_MAX;
        for (int v = t; v != s; v = parent[v]) {
            int u = parent[v];
            inc = min(inc, adj[u][parent_edge[v]].cap);
        }
        for (int v = t; v != s; v = parent[v]) {
            int u = parent[v];
            int ei = parent_edge[v];
            adj[u][ei].cap -= inc;
            adj[v][adj[u][ei].rev].cap += inc;
        }
        flow += inc;
    }
    return flow;
}

int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    int n, m, s, t;
    cin >> n >> m >> s >> t;
    adj.assign(n + 1, {});
    for (int i = 0; i < m; i++) {
        int u, v, c;
        cin >> u >> v >> c;
        add_edge(u, v, c);
    }
    cout << edmonds_karp(s, t, n) << "\n";
    return 0;
}