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

int N, M, cap[352][352], flux[352][352], x, y, z, c, dad[352], cmin, cost[352][352], used[352], D[352], source, sink;
vector < int > G[352];
bool inQ[352];
queue < int > Q;

bool bellman()
{
    for (int i=1; i<=N; ++i)
        dad[i]=D[i]=(1<<30), used[i]=0;
    inQ[source]=1; Q.push(source); D[source]=0;
    while (!Q.empty())
    {
        int nod=Q.front(); Q.pop(); inQ[nod]=0; ++used[nod];
        if (used[nod]==N) return 0;
        vector < int >::iterator it=G[nod].begin();
        for (; it!=G[nod].end(); ++it)
            if (cap[nod][*it]>flux[nod][*it] && D[*it]>D[nod]+cost[nod][*it])
            {
                D[*it]=D[nod]+cost[nod][*it]; dad[*it]=nod;
                if (!inQ[*it]) inQ[*it]=1, Q.push(*it);
            }
    }
    return (D[sink]!=(1<<30));
}

void fmcm()
{
    while (bellman())
    {
        int minim=(1<<30);
        for (int x=sink; x!=source; x=dad[x])
            if (cap[dad[x]][x]-flux[dad[x]][x]<minim)
                minim=cap[dad[x]][x]-flux[dad[x]][x];
        for (int x=sink; x!=source; x=dad[x])
            flux[dad[x]][x]+=minim, flux[x][dad[x]]-=minim;
        cmin+=D[sink]*minim;
    }
}

int main()
{
    f>>N>>M>>source>>sink;
    for (int i=1; i<=M; ++i)
    {
        f>>x>>y>>c>>z; cap[x][y]=c;
        cost[x][y]=z; cost[y][x]=-z;
        G[x].push_back(y); G[y].push_back(x);
    }

    fmcm(); g<<cmin<<'\n';
    return 0;
}