/in/foo.cc: In function 'std::string bmul(std::string, std::string)':
/in/foo.cc:10:22: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   10 |         for(int i=0;i<a.size();i++)
      |                     ~^~~~~~~~~
/in/foo.cc:14:22: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   14 |         for(int i=0;i<b.size();i++)
      |                     ~^~~~~~~~~
/in/foo.cc:18:22: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   18 |         for(int i=0;i<a.size();i++)
      |                     ~^~~~~~~~~
/in/foo.cc:20:30: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   20 |                 for(int j=0;j<b.size();j++)
      |                             ~^~~~~~~~~