#include <bits/stdc++.h>
#define DIM 351
using namespace std;
ifstream fin("fmcm.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];
queue<int> q;
vector<int> v[DIM];

int bellma()
{
    int nod;
    for(int i=1;i<=n;i++) d[i]=2000000000,h[i]=0;
    d[start]=0;h[start]=1;q.push(start);
    while(!q.empty())
    {
        nod=q.front();q.pop();h[nod]=0;
        for(auto it:v[nod])
        {
            if(c[nod][it]>f[nod][it]&&d[it]>d[nod]+k[nod][it])
            {
                d[it]=d[nod]+k[nod][it],t[it]=nod;
                if(!h[it]) q.push(it),h[it]=1;
            }
        }
    }
    if(d[fina]==2000000000) return 0;
    else 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=2000000000;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;
}