#include <fstream>
#include <cstring>
#include <vector>
#include <queue>
#include <algorithm>
using namespace std;
ifstream f("fmcm.in");
ofstream g("fmcm.out");
vector<int> a[355];
queue <int> qu;
int viz[355],csm,pred[355],n,m,pi,i,x,y,dist[355],pf,cst[355][355],cost[355][355],fl[355][355];
int bellmanford()
{
    qu.push(pi);
    for(i=1;i<=n;i++)
        dist[i]=2000000000;
    memset(viz,0,sizeof(viz));
    dist[pi]=0;
    pred[pf]=0;
    while(!qu.empty())
    {
        x=qu.front();
        qu.pop();
        viz[x]=0;
        for(vector<int>::iterator it=a[x].begin();it!=a[x].end();it++)
        {
            if(dist[x]+cost[x][*it]<dist[*it]&&fl[x][*it])
            {
                dist[*it]=dist[x]+cost[x][*it];
                pred[*it]=x;
                if(!viz[*it])
                {
                    qu.push(*it);
                    viz[*it]++;
                }
            }
        }
    }
    return pred[pf];
}
int dijkstra()
{
    return 0;
}
int main()
{
    f>>n>>m>>pi>>pf;
    for(i=1;i<=m;i++)
    {
        f>>x>>y;
        a[x].push_back(y);
        a[y].push_back(x);
        f>>fl[x][y];
        f>>cost[x][y];
        cost[y][x]=-cost[x][y];
    }
    bellmanford();
    for(i=1;i<=n;i++)
    {
        for(vector<int>::iterator it=a[i].begin();it!=a[i].end();it++)
        {
            cst[i][*it]=cost[i][*it]+(dist[i]-dist[*it]);
        }
    }
    while(bellmanford())
    {
        x=pf;
        y=2000000000;
        while(pred[x])
        {
            if(fl[pred[x]][x]<y)
                y=fl[pred[x]][x];
            x=pred[x];
        }
        x=pf;
        while(pred[x])
        {
            fl[pred[x]][x]-=y;
            fl[x][pred[x]]+=y;
            csm+=(y*cost[pred[x]][x]);
            x=pred[x];
        }
    }
    g<<csm<<'\n';
    f.close();
    g.close();
    return 0;
}