#include <bits/stdc++.h>
using namespace std;
ifstream f("fmcm.in"); ofstream g("fmcm.out");

vector <int> v[360];
int min_dist[360],tata[360],new_dist[360],dist[360];
int C[360][360],cost[360][360],flux[360][360];

void Bellman_Ford(int nod_start, int n) {
    queue <int> q;
    for(int i = 1; i <= n; i++)
        dist[i] = INT_MAX/2;

    dist[nod_start] = 0;
    q.push(nod_start);
    while(!q.empty()) {
        int nod = q.front();
        q.pop();

        for(int i = 0; i < v[nod].size(); i++) {
            int vecin = v[nod][i];
            if(flux[nod][vecin] < C[nod][vecin] && dist[vecin] > dist[nod] + cost[nod][vecin]) {
                dist[vecin] = dist[nod] + cost[nod][vecin];
                q.push(vecin);
            }
        }
    }
}

int Dijkstra(int nod_start, int n, int nod_final, int &maxflow, int &cost_total) {

    priority_queue < pair <int,int> , vector <pair <int,int > > , greater < pair <int,int > > > h;
    int nod, flux_min = INT_MAX;
    for(int i = 1; i <= n; i++) {
        min_dist[i] = INT_MAX/2;
        tata[i] = 0;
    }
    min_dist[nod_start] = 0;
    new_dist[nod_start] = 0;
    h.push({0,nod_start});

    while(!h.empty()) {
        nod = h.top().second;
        if(min_dist[nod] < h.top().first) {
            h.pop();
            continue;
        }
        else h.pop();

        for(int i = 0; i < v[nod].size(); i++) {
            int vecin = v[nod][i];
            int dist_intre = cost[nod][vecin]+dist[nod]-dist[vecin];

            if(flux[nod][vecin] < C[nod][vecin] && min_dist[vecin] > min_dist[nod] + dist_intre) {
                min_dist[vecin] = min_dist[nod] + dist_intre;
                new_dist[vecin] = new_dist[nod] + cost[nod][vecin];
                tata[vecin] = nod;
                h.push({min_dist[vecin],vecin});
            }
        }
    }

    if(min_dist[nod_final] == INT_MAX/2) return 0;
    nod = nod_final;
    while(tata[nod] != 0) {
        flux_min = min(flux_min, C[tata[nod]][nod] - flux[tata[nod]][nod]);
        nod = tata[nod];
    }

    nod = nod_final;
    while(tata[nod] != 0) {
        flux[tata[nod]][nod] += flux_min;
        flux[nod][tata[nod]] -= flux_min;
        nod = tata[nod];
    }

    maxflow += flux_min;
    cost_total += flux_min * new_dist[nod_final];
    for(int i = 1; i<=n; i++)
        dist[i] = new_dist[i];
    return 1;
}

int main() {
    int n, m, nod_start, nod_final, maxflow = 0, cost_total = 0;
    f >> n >> m >> nod_start >> nod_final;

    for(int x, y, z, c, i = 1; i <= m; i++) {
        f >> x >> y >> c >> z;
        v[x].push_back(y);
        v[y].push_back(x);
        C[x][y] = c;
        cost[x][y] = z;
        cost[y][x] = -z;
    }

    Bellman_Ford(nod_start, n);
    while(Dijkstra(nod_start, n, nod_final, maxflow, cost_total));

    g<<cost_total;
    g.close();
    return 0;
}