foo.cc: In function 'void set()':
foo.cc:15:19: warning: suggest explicit braces to avoid ambiguous 'else' [-Wdangling-else]
   15 |                 if(vin[i]==0)
      |                   ^
foo.cc: In function 'void topsort(int)':
foo.cc:23:35: warning: suggest explicit braces to avoid ambiguous 'else' [-Wdangling-else]
   23 |                                 if((--vin[edge[i].to])==0)
      |                                   ^
foo.cc:31:35: warning: suggest explicit braces to avoid ambiguous 'else' [-Wdangling-else]
   31 |                                 if((--vin[edge[i].to])==0)
      |                                   ^
foo.cc: In function 'int main()':
foo.cc:52:9: warning: this 'for' clause does not guard... [-Wmisleading-indentation]
   52 |         for(int i=1;i<=n;i++) vin[i]=vinn[i]; h1=h2=t1=t2=0;
      |         ^~~
foo.cc:52:47: note: ...this statement, but the latter is misleadingly indented as if it were guarded by the 'for'
   52 |         for(int i=1;i<=n;i++) vin[i]=vinn[i]; h1=h2=t1=t2=0;
      |                                               ^~

[Hydro](https://hydro.ac)提供评测服务