#include <iostream>
#include <vector>
#include <queue>

#define NMax 400
#define Inf 2000000000

using namespace std;

vector <int> G[NMax];
int N, Cost[NMax][NMax], S, D, Dist[NMax], Father[NMax], DistD;
int Cap[NMax][NMax], Flow[NMax][NMax], CostFM;

void Read ()
{
    freopen ("fmcm.in", "r", stdin);
    int M;
    scanf ("%d %d %d %d", &N, &M, &S, &D);
    for (; M>0; --M)
    {
        int X, Y, Z, Q;
        scanf ("%d %d %d %d", &X, &Y, &Z, &Q);
        G[X].push_back (Y);
        Cap[X][Y]=Z;
        Cost[X][Y]=Q;
        G[Y].push_back (X);
        Cost[Y][X]=-Q;
    }
}

void Print ()
{
    freopen ("fmcm.out", "w", stdout);
    printf ("%d\n", CostFM);
}

inline int Min (int a, int b)
{
    if (a<b)
    {
        return a;
    }
    return b;
}

bool BellmanFord (int Start)
{
    queue <int> Q;
    bool InQ[NMax];
    for (int i=1; i<=N; ++i)
    {
        Dist[i]=Inf;
        InQ[i]=false;
    }
    Dist[Start]=0;
    Q.push (Start);
    InQ[Start]=true;
    while (!Q.empty ())
    {
        int X=Q.front ();
        Q.pop ();
        InQ[X]=false;
        for (unsigned i=0; i<G[X].size (); ++i)
        {
            int V=G[X][i];
            int C=Cost[X][V];
            if (Dist[X]+C<Dist[V] and Cap[X][V]-Flow[X][V]>0)
            {
                Dist[V]=Dist[X]+C;
                Father[V]=X;
                if (!InQ[V])
                {
                    Q.push (V);
                    InQ[V]=true;
                }
            }
        }
    }
    if (Dist[D]!=Inf)
    {
        return true;
    }
    return false;
}

void EdmondsKarp ()
{
    BellmanFord (S);
    int CurrentFlow=Inf;
    do
    {
        for (int X=D; X!=S; X=Father[X])
        {
            CurrentFlow=Min (CurrentFlow, Cap[Father[X]][X]-Flow[Father[X]][X]);
        }
        for (int X=D; X!=S; X=Father[X])
        {
            Flow[Father[X]][X]+=CurrentFlow;
            Flow[X][Father[X]]-=CurrentFlow;
        }
        DistD+=Dist[D];
        CostFM+=(CurrentFlow*Dist[D]);
    }
    while (BellmanFord (S));
}

int main()
{
    Read ();
    EdmondsKarp ();
    Print ();
    return 0;
}