#include <fstream>
#include <vector>
#include <queue>
#include <algorithm>
using namespace std;
ifstream f("fmcm.in");
ofstream g("fmcm.out");

int N, M, L, R, x, y, c1, c2, cap[355][355], cost[355][355], D[355], flux[355][355], dad[355], inQ[355], start, dest, sol;
vector < int > G[355];
queue < int > Q;

int bellman(int srs, int sink)
{
    for (int i=1; i<=N; ++i)
        D[i]=(1<<30);
    Q.push(srs); D[srs]=0; inQ[srs]=1;

    while (Q.size())
    {
        int nod=Q.front(); Q.pop(); inQ[nod]=0;
        vector <int>::iterator it=G[nod].begin();
        for (; it!=G[nod].end(); ++it)
            if (D[nod]+cost[nod][*it]<D[*it] && cap[nod][*it]>flux[nod][*it])
            {
                D[*it]=D[nod]+cost[nod][*it]; dad[*it]=nod;
                if (!inQ[*it])
                    inQ[*it]=1, Q.push(*it);
            }
    }
    if (D[sink]!=(1<<30))
    {
        int minim=(1<<30);
        for (int x=sink; x!=srs; x=dad[x])
            minim=min(minim, cap[dad[x]][x]-flux[dad[x]][x]);
        for (int x=sink; x!=srs; x=dad[x])
            flux[dad[x]][x]+=minim, flux[x][dad[x]]-=minim;
        return minim;
    }
    return 0;
}

void fmcm(int srs, int sink)
{
    for (int j=bellman(srs, sink); j; j=bellman(srs, sink))
        sol+=j*D[sink];
}

int main()
{
    f>>N>>M>>start>>dest;
    for (int i=1; i<=M; ++i)
    {
        f>>x>>y>>c1>>c2;
        G[x].push_back(y);
        G[y].push_back(x);
        cap[x][y]=c1; cost[x][y]=c2;
        cost[y][x]=-c2;
    }

    fmcm(start, dest);
    g<<sol<<'\n';
    return 0;
}