foo.cc: In function 'int Secondz(std::string&)':
foo.cc:10:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   10 |         for(int i=0; i<s.length(); i++)
      |                      ~^~~~~~~~~~~
foo.cc: In function 'int Zero(std::string&)':
foo.cc:31:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   31 |         for(int i=0; i<s.length(); i++)
      |                      ~^~~~~~~~~~~

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