#include <bits/stdc++.h>
#define INF 0x3f3f3f3f
#define NMAX 355

using namespace std;

ifstream f("fmcm.in");
ofstream g("fmcm.out");

int n, m, dist[NMAX], flux, cost, t[NMAX], c[NMAX][NMAX], F[NMAX][NMAX], costuri[NMAX][NMAX];
int start, stop;
bitset <NMAX> v;
vector <pair <int, int>> edges[NMAX];
queue <int> q;

bool bf()
{
    bool ok = 0;
    for(int i = 1; i <= n; i++)
        dist[i] = INF, v[i] = 0;
    dist[start] = 0;
    v[start] = 1;
    q.push(start);
    while(!q.empty())
    {
        int nod = q.front();
        q.pop();
        v[nod] = 0;
        for(auto child : edges[nod])
            if(c[nod][child.first] > F[nod][child.first] && dist[child.first] > dist[nod] + child.second)
            {
                dist[child.first] = dist[nod] + child.second;
                t[child.first] = nod;
                if(child.first == stop)
                    ok = 1;
                if(!v[child.first])
                {
                    q.push(child.first);
                    v[child.first] = 1;
                }
            }
    }
    return ok;
}

int main()
{
    f >> n >> m >> start >> stop;

    for(int i = 1; i <= m; i++)
    {
        int x, y, cost, cap;
        f >> x >> y >> cap >> cost;
        c[x][y] = cap;
        costuri[x][y] = cost;
        costuri[y][x] = -cost;
        edges[x].push_back(make_pair(y, cost));
        edges[y].push_back(make_pair(x, -cost));
    }

    while(bf())
    {
        int minim = INF;
        int k = stop;
        while(k != start)
        {
            minim = min(minim, c[t[k]][k] - F[t[k]][k]);
            k = t[k];
        }

        k = stop;
        while(k != start)
        {
            F[t[k]][k] += minim;
            F[k][t[k]] -= minim;
            cost += costuri[t[k]][k] * minim;
            k = t[k];
        }
    }

    g << cost;
    return 0;
}