/in/foo.cc: In function 'void topsort()':
/in/foo.cc:27:12: warning: suggest explicit braces to avoid ambiguous 'else' [-Wdangling-else]
    }else if(!--vin[vet[h][i]])
            ^
/in/foo.cc: In function 'int main()':
/in/foo.cc:38:16: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for(int j=0;j<min(a[i].length(),a[i+1].length());j++)
               ~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~