#include<bits/stdc++.h>
using namespace std;

typedef struct lnod {
    int nod,cost,cap,flow,last;
}nod;

const int INF=1e9+69*69;

int i,n,m,flow,rs,start,fin,x,y,cap,cost;
int q[355],tata[355],d[355],id[355],qh,qt,poz[355];
vector<nod> g[355];

void add(int x,int y,int cap,int cost) {
    nod r1={y,cost,cap,0,(int)g[y].size()};
    nod r2={x,-cost,0,0,(int)g[x].size()};

    g[x].push_back(r1);
    g[y].push_back(r2);
}

int Update() {
    int addflow=INF;

    for(x=fin;x!=start;x=tata[x])
    {
      int p=tata[x],pos=poz[x];
      addflow=min(addflow,g[p][pos].cap-g[p][pos].flow);
    }

    for(x=fin;x!=start;x=tata[x])
    {
      int p=tata[x],pos=poz[x];
      int rev=g[p][pos].last;

      g[p][pos].flow+=addflow;
      g[x][rev].flow-=addflow;
      rs+=g[p][pos].cost*addflow;
    }

    return addflow;
}

int main()
{
  ifstream cin("fmcm.in");
  ofstream cout("fmcm.out");

  ios_base::sync_with_stdio(0); cin.tie(0);

  for(cin>>n>>m>>start>>fin;m;--m)
  {
    cin>>x>>y>>cap>>cost;
    add(x,y,cap,cost);
  }

  while(1)
  {
    for(i=0;i<=n+1;++i) id[i]=0,d[i]=INF;

    qh=qt=0; q[qt++]=start; d[start]=0;

    while(qh!=qt)
    {
      x=q[qh++]; id[x]=2;
      if(qh==n) qh=0;

      for(i=0;i<(int)g[x].size();++i)
      {
        nod &r=g[x][i];
        if(r.flow<r.cap && d[r.nod]>d[x]+r.cost)
        {
          d[r.nod]=d[x]+r.cost;
          if(!id[r.nod])
          {
            q[qt++]=r.nod;
            if(qt==n) qt=0;
          }
          else if(id[r.nod]==2)
               {
                 if(--qh==-1) qh=n-1;
                 q[qh]=r.nod;
               }

          id[r.nod]=1; tata[r.nod]=x; poz[r.nod]=i;
        }
      }
    }

    if(d[fin]==INF) break;

    flow+=Update();
  }

  cout<<rs<<'\n';

 return 0;
}