foo.cc: In function 'long long int LongestStr(std::string)':
foo.cc:8:15: warning: comparison of integer expressions of different signedness: 'long long int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
    8 |  for(int i=0;i<s.size();i++)
      |              ~^~~~~~~~~
foo.cc:21:15: warning: comparison of integer expressions of different signedness: 'long long int' and 'std::vector<long long int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   21 |  for(int i=0;i<v.size();++i)
      |              ~^~~~~~~~~

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