#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,nod,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;
    }
    d[start]=0;h[start]=1;
    co.clear();co.push_back(start);
    while(co.empty())
    {
        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)
            {
                d[vecin]=d[nod]+cost;
                t[vecin]=nod;
                if(h[vecin]==0)
                {
                    co.push_back(vecin);
                    h[vecin]=1;
                }
            }
        }
    }
    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())
    {
        mini=inf;nod=fina;
        while(t[nod])
        {
            mini=min(mini,c[t[nod]][nod]-f[t[nod]][nod]);
            nod=t[nod];
        }
        nod=fina;
        while(t[nod])
        {
            sol+=mini*k[t[nod]][nod];
            f[t[nod]][nod]+=mini;
            f[nod][t[nod]]-=mini;
            nod=t[nod];
        }
    }
    fout<<sol;
    return 0;
}