#include <fstream>
#include <vector>
#include <queue>
using namespace std;
#define MAXN 355
#define INF 0x3f3f3f3f
ifstream cin("fmcm.in");
ofstream cout("fmcm.out");

queue<int> coada;
vector<int> graf[MAXN];
int capacitate[MAXN][MAXN], cost[MAXN][MAXN], flux[MAXN][MAXN], dist[MAXN], tata[MAXN];
int n, m, st, fin, flux_crt, flux_maxim, cost_crt, cost_maxim;

bool bellman(int start, int fin)
{
    int i, crt, urm;
    for(i = 1; i<=n; i++)
    {
        tata[i] = 0;
        dist[i] = INF;
    }
    dist[start] = 0;
    coada.push(start);

    while(!coada.empty())
    {
        crt = coada.front(); coada.pop();
        for(i=0; i<graf[crt].size(); i++)
        {
            urm = graf[crt][i];
            if(dist[urm] > dist[crt] + cost[crt][urm] && capacitate[crt][urm] > flux[crt][urm] )
            {
                dist[urm] = dist[crt] + cost[crt][urm];
                tata[urm] = crt;
                coada.push(urm);
            }
        }
    }
    if(dist[fin] == INF)
        return 0;
    return 1;

}

int main()
{
    int i, j, x, y, z, w;
    cin >> n >> m >> st >> fin;
    for(i=1; i<=m; i++)
    {
        cin>>x>>y>>z>>w;
        graf[x].push_back(y);
        graf[y].push_back(x);
        capacitate[x][y] = z;
        cost[x][y] = w;
        cost[y][x] = -w;
    }

    while( bellman(st, fin) )
    {
        flux_crt = INF;
        for(i=fin; i!=st; i=tata[i])
            flux_crt = min(flux_crt, capacitate[tata[i]][i] - flux[tata[i]][i]);

        if(flux_crt)
        {
            cost_crt =0;
            for(i=fin; i!=st; i=tata[i])
            {
                flux[tata[i]][i] += flux_crt;
                flux[i][tata[i]] -= flux_crt;
                cost_crt += cost[tata[i]][i];
            }

            flux_maxim += flux_crt;
            cost_maxim += cost_crt*flux_crt;
        }

    }

    cout<<<cost_maxim;
    return 0;
}