foo.cc: In function 'void Match(std::string&)':
foo.cc:8:9: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
    8 |  while(i<s.length())
      |        ~^~~~~~~~~~~
foo.cc:10:10: 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(; i<s.length(); i++)
      |         ~^~~~~~~~~~~

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