/in/foo.cc: In function 'void match(std::string)':
/in/foo.cc:36:22: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   36 |         for(int i=0;i<=s.size();i++)
      |                     ~^~~~~~~~~~
/in/foo.cc:44:22: warning: comparison of integer expressions of different signedness: 'int' and 'std::stack<long long int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   44 |         for(int i=0;i<=stk.size();++i) {
      |                     ~^~~~~~~~~~~~