#include <fstream>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <vector>
#include <queue>
#include <algorithm>
using namespace std;
//ifstream f("fmcm.in");
ofstream g("fmcm.out");
//ofstream g("date.out");
vector<int> a[355];
queue <int> qu;
pair<int,int> per;
int xit,viz[355],csm,pred[355],n,m,pi,i,x,y,dist[355],pf,cst[355][355],cost[355][355],fl[355][355];
priority_queue <pair<int,int>,vector<pair<int,int> >,greater<pair<int,int> > > q;
void 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++)
        {
            xit=*it;
            if(dist[x]+cost[x][xit]<dist[xit]&&fl[x][xit])
            {
                dist[xit]=dist[x]+cost[x][xit];
                pred[xit]=x;
                if(!viz[xit])
                {
                    qu.push(xit);
                    viz[xit]++;
                }
            }
        }
    }
}
int dijkstra()
{
    for(i=1;i<=n;i++)
        dist[i]=2000000000;
    q.push(pair<int,int>(0,pi));
    dist[pi]=0;
    pred[pf]=0;
    while(!q.empty())
    {
        per=q.top();
        q.pop();
        x=per.second;
        if(dist[x]==per.first)
        {
            for(vector<int>::iterator it=a[x].begin();it!=a[x].end();it++)
            {
                y=*it;
                if(dist[x]+cst[x][y]<dist[y]&&fl[x][y])
                {
                    dist[y]=dist[x]+cst[x][y];
                    q.push(pair<int,int>(dist[y],y));
                    pred[y]=x;
                }
            }
        }
    }
    return pred[pf];
}
int main()
{
    freopen("fmcm.in","r",stdin);
    //freopen("date.in","r",stdin);
    scanf("%d",&n);
    scanf("%d",&m);
    scanf("%d",&pi);
    scanf("%d",&pf);
    //f>>n>>m>>pi>>pf;
    for(i=1;i<=m;i++)
    {
        //f>>x>>y;
        scanf("%d",&x);
        scanf("%d",&y);
        a[x].push_back(y);
        a[y].push_back(x);
        scanf("%d",&fl[x][y]);
        //f>>fl[x][y];
        scanf("%d",&cost[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++)
        {
            xit=*it;
            cst[i][xit]=cost[i][xit]+(dist[i]-dist[xit]);
        }
    }
    while(dijkstra())
    {
        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';
    return 0;
}