void toposort(TD g[],int n)
{  int top,m,k,j;
   JD *p;
   top=0; m=0;
   for(j=1;j<=n;j++)
     if(g[j].in==0)
     {  g[j].in=top; 
        top=j;
     }
   while(top>0)
   {  j=top;
      top=g[top].in;
      printf("%d\n",j);
      m++;
      p=g[j].link;
      while(p!=NULL)
      {  k=p->vex;
         g[k].in--;
         if(g[k].in==0)
         {   g[k].in=top;
             top=k;
         }
         p=p->next;
      }
   }
   printf("m=%d\n",m);
   if(m<n)  printf("The network has a cycle\n");
}