/in/foo.cc: In function 'std::string Jia(const string&, const string&)':
/in/foo.cc:39:15: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   39 |  for(int i=0;i<str1.size();++i)
      |              ~^~~~~~~~~~~~
/in/foo.cc:45:25: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   45 |  for(int j=str1.size();j<Outstr.size();++j)
      |                        ~^~~~~~~~~~~~~~
/in/foo.cc: In function 'int main()':
/in/foo.cc:88:16: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::__cxx11::basic_string<char> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   88 |   for(int i=0;i<Outstr.size();++i)
      |               ~^~~~~~~~~~~~~~