#include <fstream>
#include <queue>
#define DIM 351
#define inf 2000000000
using namespace std;
ifstream fin("fmcme.in");
ofstream fout("fmcm.out");
int n,m,i,mini,ve,a,b,cap,sol,start,fina,pret;
int c[DIM][DIM], f[DIM][DIM], k[DIM][DIM];
int d[DIM], t[DIM], h[DIM];
deque<int> co;
vector<int> v[DIM];


int bellma()
{
    int i,nod,vecin,cost;
    for(i=1;i<=n;i++)
    {
        d[i]=inf;
        t[i]=0;
        h[i]=0;
    }
    co.clear();
    d[start]=0;h[start]=1;
    co.push_back(start);
    while(co.size())
    {
        nod=co.front();
        co.pop_front();
        h[nod]=0;
        for(i=0;i<v[nod].size();i++)
        {
            vecin=v[nod][i];
            cost=k[nod][vecin];
            if(f[nod][vecin]<c[nod][vecin]&&d[vecin]>d[nod]+cost)
            {
                if(h[vecin]==0)
                {
                    co.push_back(vecin);
                    h[vecin]=1;
                }
                d[vecin]=d[nod]+cost;
                t[vecin]=nod;
            }
        }
    }
    if(d[fina]==inf)
        return 0;
    return 1;
}

int main()
{
    fin>>n>>m>>start>>fina;
    for(i=1;i<=m;i++)
    {
        fin>>a>>b>>cap>>pret;
        v[a].push_back(b);
        v[b].push_back(a);
        c[a][b]=cap;
        k[a][b]=pret;
        k[b][a]=-pret;
    }
    while(bellma())
    {
        ve=t[fina];
        a=ve;b=fina;
        mini=c[ve][fina]-f[ve][fina];
        while(a)
        {
            mini=min(mini, c[a][b]-f[a][b]);
            b=a;a=t[a];
        }
        a=ve;b=fina;
        while(a)
        {
            f[a][b]+=mini;
            f[b][a]-=mini;
            b=a;a=t[a];
        }
        sol+=mini*d[fina];
    }
    fout<<sol;
    return 0;
}