/in/foo.cc: In function 'std::string bigSubtract(std::string, std::string)':
/in/foo.cc:22:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   22 |     for (int i = 0; i < a.length(); i++) {
      |                     ~~^~~~~~~~~~~~
/in/foo.cc:24:25: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   24 |         int digitB = (i < b.length()) ? b[i] - '0' : 0;
      |                       ~~^~~~~~~~~~~~