/// complexity : m^2 * n
#include<bits/stdc++.h>
using namespace std;

const int N = 1004, oo = 1e9+7;
int n, m, S, T, c[N][N];
vector<int> adj[N];

queue<int> Q;
int tr[N];
bool vis[N];

bool BFS() {
    for (int i = 1; i <= n; ++i) vis[i] = false, tr[i] = 0;
    while (Q.size()) Q.pop();
    vis[S] = true; Q.push(S);
    while (Q.size()) {
        int u = Q.front(); Q.pop();
        if (u == T) return true;
        for (int v : adj[u]) {
            if (c[u][v] <= 0 || vis[v]) continue;
            tr[v] = u; vis[v] = true; Q.push(v);
        }
    }
    return false;
}

vector<int> Path;
int res = 0;

void FixGraph() {
    int v = T; Path.clear();
    while (v != S) { Path.push_back(v); v = tr[v]; } Path.push_back(S);
    reverse(Path.begin(), Path.end());
    int minCost = oo;
    for (int i = 0; i < Path.size()-1; ++i) minCost = min(minCost, c[Path[i]][Path[i+1]]);
    for (int i = 0; i < Path.size()-1; ++i) {
        int u = Path[i], v = Path[i+1];
        c[u][v] -= minCost; c[v][u] += minCost;
    }
    res += minCost;
}

void sol() {
    while (true) {
        if (!BFS()) break;
        FixGraph();
    }
    cout << res;
}

int main() {
    ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);

    cin >> n >> m >> S >> T;
    int u, v, w;
    for (int i = 1; i <= m; ++i) {
        cin >> u >> v >> w;
        adj[u].push_back(v); adj[v].push_back(u);
        c[u][v] = w;
    }

    sol();

    return 0;
}