#include <bits/stdc++.h>

using namespace std;
class mcmf {
    const int inf = 1e9;
    vector <vector <int>> e, g, c;
    int s, t;
    vector <int> d, from;
    vector <bool> inq;
public:
    mcmf(int n, int s, int t) : e(n + 1, vector <int>(n + 1, 0)), g(n + 1), c(e), s(s), t(t), d(n + 1), from(n + 1), inq(n + 1, false) {}
    void add_edge(int u, int v, int w, int co) {
        g[u].push_back(v); g[v].push_back(u);
        e[u][v] = w;
        c[u][v] = co;
        e[v][u] = 0;
        c[v][u] = -co;
    }
    pair <int, int> bellman_ford() {
        queue <int> q;
        q.push(s);
        d[s] = 0; from[s] = s;
        while(!q.empty()) {
            int u = q.front();
            q.pop();
            inq[u] = false;
            for(int v : g[u]) {
                if(e[u][v] && d[u] + c[u][v] < d[v]) {
                    d[v] = d[u] + c[u][v];
                    from[v] = u;
                    if(!inq[v]) {
                        q.push(v);
                        inq[v] = true;
                    }
                }
            }
        }
        if(d[t] != inf) {
            int flow = inf;
            for(int i = t; i != s; i = from[i]) flow = min(flow, e[from[i]][i]);
            for(int i = t; i != s; i = from[i]) {
                e[from[i]][i] -= flow;
                e[i][from[i]] += flow;
            }
            return {flow, d[t] * flow};
        }
        return {0, 0};
    }
    pair <int, int> flow() {
        int flow = 0, cost = 0;
        fill(d.begin(), d.end(), inf);
        pair <int, int> fc = bellman_ford();
        while(fc.first != 0) {
            flow += fc.first;
            cost += fc.second;
            fill(d.begin(), d.end(), inf);
            fc = bellman_ford();
        }
        return {flow, cost};
    }
};

int main()
{
    ifstream cin("fmcm.in");
    ofstream cout("fmcm.out");
    int n, m, s, t;
    cin >> n >> m >> s >> t;
    mcmf F(n, s, t);
    for(int i = 0, u, v, w, c; i < m; i++) {
        cin >> u >> v >> w >> c;
        F.add_edge(u, v, w, c);
    }
    auto f = F.flow();
    cout << f.second << "\n";
    return 0;
}