#include <queue>
#include <bitset>
#include <cstdlib>
#include <fstream>
#include <algorithm>
#define Nmax 400
#define oo 0x3f3f3f3f

/*
 *
 */
using namespace std;
typedef pair< int, int > pr;
int N, source, sink;
int d[Nmax], f[Nmax];
int C[Nmax][Nmax];
vector< pr > G[Nmax];
vector< pr >::const_iterator it, iend;
class cmp
{
public:
    inline bool operator() ( const int& x, const int& y ) const
    {
        return d[x] > d[y];
    }
};
bitset< Nmax > inH;
priority_queue< int, vector< int >, cmp > pQ;
inline bool find_path( void )
{
    int x;
    fill( d+1, d+N+1, oo );
    d[source]=0;
    inH.flip(source);
    for( pQ.push(source); !pQ.empty(); )
    {
        x=pQ.top(); pQ.pop();
        inH.flip(x);
        for( it=G[x].begin(), iend=G[x].end(); it < iend; ++it )
        {
            if( source == it->first )
                continue;
            if( C[x][it->first] > 0 && d[x]+it->second < d[it->first] )
            {
                f[it->first]=x;
                d[it->first]=d[x]+it->second;
                if( false == inH.test(it->first) )
                {
                    pQ.push(it->first);
                    inH.set(it->first);
                }
            }
        }
    }
    inH&=0;
    return oo != d[sink];
}
int main( void )
{
    int M, x, y, c;
    ifstream in( "fmcm.in" );
    for( in>>N>>M>>source>>sink; M; --M )
    {
        in>>x>>y;
        in>>C[x][y]>>c;
        G[x].push_back( pr( y, c ) );
        G[y].push_back( pr( x, -c ) );
    }
    for( x=0; find_path(); )
    {
        c=oo;
        for( y=sink; f[y]; y=f[y] )
            if( c > C[f[y]][y] )
                c=C[f[y]][y];
        for( y=sink; f[y]; y=f[y] )
        {
            C[f[y]][y]-=c;
            C[y][f[y]]+=c;
        }
        x+=c*d[sink];
    }
    ofstream out( "fmcm.out" );
    out<<x<<'\n';
    return EXIT_SUCCESS;
}