foo.cc: In function 'int main()':
foo.cc:18:30: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   18 |                 for(int j=0;j<s.size();j++)
      |                             ~^~~~~~~~~
foo.cc:21:27: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   21 |                 for( i=0;i<s.size();i++)
      |                          ~^~~~~~~~~
foo.cc:43:21: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   43 |                 if(i==s.size()) cout<<"Case #"<<cnt<<": "<<"YES"<<endl;
      |                    ~^~~~~~~~~~

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