foo.cc: In function 'int main()':
foo.cc:15:7: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   15 |   if(i<s.length())
      |      ~^~~~~~~~~~~
foo.cc:18:12: warning: comparison of integer expressions of different signedness: 'int' and 'const size_type' {aka 'const long unsigned int'} [-Wsign-compare]
   18 |    if(index!=string::npos)
      |       ~~~~~^~~~~~~~~~~~~~

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