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

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

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

void minflow(int sursa, int sink)
{
    for (; bellman(sursa); )
    {
        int minim=(1<<30);
        for (int x=sink; x!=sursa; x=prec[x])
            if (cap[prec[x]][x]-flux[prec[x]][x]<minim)
                minim=cap[prec[x]][x]-flux[prec[x]][x];
        if (minim && minim<(1<<30))
        {
            for (int x=sink; x!=sursa; x=prec[x])
                flux[prec[x]][x]+=minim, flux[x][prec[x]]-=minim;
            costmin+=minim*D[sink];
        }
    }
}

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

    minflow(source, sink); g<<costmin<<'\n';
    return 0;
}