foo.cc: In function 'void my_add(std::string, std::string)':
foo.cc:8:30: 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<a.length();i++){
      |                             ~^~~~~~~~~~~
foo.cc:17:30: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   17 |                 for(int i=0;i<a.length();i++){
      |                             ~^~~~~~~~~~~
foo.cc: In function 'int main()':
foo.cc:43:22: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   43 |         for(int i=0;i<=m.length();i++){
      |                     ~^~~~~~~~~~~~

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