#include<fstream>
#include<iostream>
#include<vector>
#define DN 355
#define pb push_back
#define x first
#define y second
#define DM 12505
#include<queue>
using namespace std;
ifstream fin("fmcm.in");
ofstream fout("fmcm.out");
int n,m,s,d,dist[DN],f[DN][DN],rez,pr[DN];
int g,h,c,z,fmin;
int cap[DN][DN],cost[DN][DN];
vector<int >v[DN];
priority_queue<pair<int,int> >q;
int dijkstra()
{
    int nod,cs;
    for(int i=1;i<=n;i++)
        dist[i]=(1<<28);
    dist[s]=0;
    q.push({0,s});
    while(!q.empty())
    {
        nod=q.top().y;
        cs=-q.top().x;
        q.pop();
        if(cs!=dist[nod]||nod==d)
            continue;
        for(auto i:v[nod])
            if(f[nod][i]<cap[nod][i])
                if(cs+cost[nod][i]<dist[i])
                {
                    pr[i]=nod;
                    dist[i]=cs+cost[nod][i];
                    q.push({-dist[i],i});
                }
    }
    if(dist[d]==(1<<28))
        return 0;
    nod=d;
    fmin=(1<<28);
    for(auto i:v[d])
    {
        pr[d]=i;
        nod=d;
        while(nod!=s)
        {
            fmin=min(fmin,cap[pr[nod]][nod]-f[pr[nod]][nod]);
            nod=pr[nod];
        }
    }
    nod=d;
    for(auto i:v[d])
    {
        pr[d]=i;
        nod=d;
        while(nod!=s)
        {
            f[pr[nod]][nod]+=fmin;
            f[nod][pr[nod]]-=fmin;
            nod=pr[nod];
        }
    }
    rez+=fmin*dist[d];
    return 1;
}
int main()
{
    fin>>n>>m>>s>>d;
    for(int i=1;i<=m;i++)
    {
        fin>>g>>h>>c>>z;
        cap[g][h]=c;
        cost[g][h]=z;
        cost[h][g]=-z;
        v[g].pb(h);
        v[h].pb(g);
    }
    while(dijkstra());
    fout<<rez;
}