#include <bits/stdc++.h>

using namespace std;

const int Nmax = 360;
const int inf = 1e9;

struct NODE
{
    int nod;
    int dist;

    NODE(){}
    NODE( const int a = 0, const int b = 0 ) : nod( a ), dist( b ) {}

    bool operator < ( const NODE &N ) const
    {
        return dist > N.dist;
    }
};

vector <int> G[Nmax + 1];
priority_queue <NODE> MinHeap;

int Cost[Nmax + 1][Nmax + 1];
int C[Nmax + 1][Nmax + 1];
int F[Nmax + 1][Nmax + 1];
int tata[Nmax + 1], dist[Nmax + 1], in_q[Nmax + 1], coada[Nmax + 1];


int N, M;

void BellmanFord( int S, int D )
{
    for ( int i = 1; i <= N; ++i )
    {
        dist[i] = inf;
    }

    int st, dr;
    dist[S] = 0;
    coada[st = dr = 1] = S;
    in_q[S] = 1;

    while ( st <= dr )
    {
        int nod = coada[ st++ ];
        in_q[nod] = 0;

        for ( auto x: G[nod] )
        {
            if ( dist[x] > dist[nod] + Cost[nod][x] && C[nod][x] > F[nod][x] )
            {
                dist[x] = dist[nod] + Cost[nod][x];

                if ( !in_q[x] )
                {
                    in_q[x] = 1;
                    coada[ ++dr ] = x;
                }
            }
        }
    }
}

void init( int S, int D )
{
    for ( int i = 1; i <= N; ++i )
    {
        for ( auto x: G[i] )
        {
            if ( dist[x] != inf && dist[i] != inf )
            {
                Cost[i][x] += ( dist[i] - dist[x] );
            }
        }
    }

    for ( int i = 1; i <= N; ++i )
    {
        dist[i] = inf;
        tata[i] = 0;
    }

    dist[S] = 0;
}

int Dijkstra( int S, int D )
{
    init( S, D );

    MinHeap.push( NODE( S, 0 ) );

    while ( MinHeap.size() )
    {
        int nod = MinHeap.top().nod;
        int ddd = MinHeap.top().dist;

        MinHeap.pop();

        if ( dist[nod] != ddd) continue;

        for ( auto x: G[nod] )
        {
            if ( dist[x] > dist[nod] + Cost[nod][x] && C[nod][x] > F[nod][x] )
            {
                dist[x] = dist[nod] + Cost[nod][x];
                tata[x] = nod;
                MinHeap.push( NODE( x, dist[x] ) );
            }
        }
    }

    return ( dist[D] != inf );
}

long long Edmonds_Karp( int S, int D )
{
    long long costFlow = 0;
    long long flow = 0;
    int fmin, distD = dist[D];

    while ( Dijkstra( S, D ) )
    {
        fmin = inf;

        for ( int nod = D; nod != S; nod = tata[nod] )
                fmin = min( fmin, C[ tata[nod] ][nod] - F[ tata[nod] ][nod] );

        for ( int nod = D; nod != S; nod = tata[nod] )
        {
            F[ tata[nod] ][nod] += fmin;
            F[nod][ tata[nod] ] -= fmin;
        }

        flow += fmin;
        distD += dist[D];
        costFlow += fmin * distD;
    }

    return costFlow;
}

int main()
{
    ifstream f("fmcm.in");
    ofstream g("fmcm.out");

    int S, D;

    f >> N >> M >> S >> D;

    for ( int i = 1, a, b, c, d; i <= M; ++i )
    {
        f >> a >> b >> c >> d;

        G[a].push_back( b );
        G[b].push_back( a );

        C[a][b] = c;
        Cost[a][b] = +d;
        Cost[b][a] = -d;
    }

    BellmanFord( S, D );
    g << Edmonds_Karp( S, D ) << "\n";

    return 0;
}