/in/foo.cc: In function 'bool issimilar(std::__cxx11::string, std::__cxx11::string)':
/in/foo.cc:11:9: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  while(i<a.size())
        ~^~~~~~~~~
/in/foo.cc:22:1: warning: control reaches end of non-void function [-Wreturn-type]
 }
 ^