foo.cc: In function ‘int main()’:
foo.cc:13:33: warning: format ‘%d’ expects argument of type ‘int*’, but argument 2 has type ‘bool*’ [-Wformat=]
   13 |                         scanf("%d",&ch);
      |                                ~^  ~~~
      |                                 |  |
      |                                 |  bool*
      |                                 int*
foo.cc:21:30: warning: comparison of integer expressions of different signedness: ‘int’ and ‘std::vector<int>::size_type’ {aka ‘long unsigned int’} [-Wsign-compare]
   21 |                 for(int i=0;i<a[v].size();i++)
      |                             ~^~~~~~~~~~~~