foo.cc: In function ‘bool is_similar(std::string, std::string)’:
foo.cc:9:22: warning: comparison of integer expressions of different signedness: ‘int’ and ‘std::__cxx11::basic_string<char>::size_type’ {aka ‘long unsigned int’} [-Wsign-compare]
    9 |         for(int i=0;i<a.size();i++)
      |                     ~^~~~~~~~~
foo.cc:23:1: warning: control reaches end of non-void function [-Wreturn-type]
   23 | }
      | ^