/in/foo.cc: In function 'void set()':
/in/foo.cc:15:5: warning: suggest explicit braces to avoid ambiguous 'else' [-Wdangling-else]
   if(vin[i]==0) 
     ^
/in/foo.cc: In function 'void topsort(int)':
/in/foo.cc:23:7: warning: suggest explicit braces to avoid ambiguous 'else' [-Wdangling-else]
     if((--vin[edge[i].to])==0)
       ^
/in/foo.cc:31:7: warning: suggest explicit braces to avoid ambiguous 'else' [-Wdangling-else]
     if((--vin[edge[i].to])==0)
       ^
/in/foo.cc: In function 'int main()':
/in/foo.cc:52:2: warning: this 'for' clause does not guard... [-Wmisleading-indentation]
  for(int i=1;i<=n;i++) vin[i]=vinn[i]; h1=h2=t1=t2=0;
  ^~~
/in/foo.cc:52:40: note: ...this statement, but the latter is misleadingly indented as if it were guarded by the 'for'
  for(int i=1;i<=n;i++) vin[i]=vinn[i]; h1=h2=t1=t2=0;
                                        ^~