/in/foo.cc: In function 'int main()':
/in/foo.cc:8:22: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
    8 |         for(int i=0;i<n.size();i++)
      |                     ~^~~~~~~~~
/in/foo.cc:11:31: warning: array subscript has type 'char' [-Wchar-subscripts]
   11 |                         a[n[i]]++;
      |                               ^
/in/foo.cc:15:34: warning: array subscript has type 'char' [-Wchar-subscripts]
   15 |                 for(int j=1;j<=a[i];j++)
      |                                  ^