#include<fstream.h>
#define N 350
int n,m,k,c[N][N],f[N][N],p,z,i,s,d,pre[N],t,l,h[N],poz[N],j,g[N][N],deg[N],o[N][N],r,w,q;
long e,b[N];
int main()
{ifstream f1("fmcm.in");
ofstream f2("fmcm.out");
f1>>n>>m>>s>>d;
s--,d--;
while(m--)
          {f1>>i>>j>>p>>z;
          i--,j--,g[i][deg[i]++]=j,g[j][deg[j]++]=i,o[i][j]=z,o[j][i]=-z,c[i][j]=p;}
while(1)      
          {for(t=0;t<n;t++)
                   poz[t]=-1,b[t]=3000;
          b[s]=l=0,r=3000,h[l++]=s,pre[d]=-1;
          while(l)
                   {i=h[0],poz[i]=-1,h[0]=h[--l],poz[h[0]]=0;
                   for(k=0;k<deg[i];k++)
                   if(c[i][g[i][k]]>f[i][g[i][k]]&&b[g[i][k]]>b[i]+o[i][g[i][k]])
                               {b[g[i][k]]=b[i]+o[i][g[i][k]],pre[g[i][k]]=i;
                               if(poz[g[i][k]]==-1)
                                      {poz[g[i][k]]=j=l,h[l++]=g[i][k];
                                      for(;j>>1;j>>=1)
                                              p=h[j],h[j]=h[j>>1],h[j>>1]=p,poz[h[j]]=j,poz[h[j>>1]]=j>>1;}}}
          if(pre[d]==-1)
                   break;
          for(q=d;q!=s;q=pre[q])
          if(r>c[pre[q]][q]-f[pre[q]][q])
                   r=c[pre[q]][q]-f[pre[q]][q];
          for(w=d;w!=s;w=pre[w])
                   f[pre[w]][w]+=r,f[w][pre[w]]-=r;
          e+=b[d]*r;}
f2<<e;    
f1.close();
f2.close();
return 0;}