foo.cc: In function 'int main()':
foo.cc:13:18: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   13 |  for(int i = 0;i < s.size();i++)if(s[i]>='A'&&s[i]<='Z')s[i]+=32;
      |                ~~^~~~~~~~~~
foo.cc:14:18: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   14 |  for(int i = 1;i < s.size();i++)
      |                ~~^~~~~~~~~~

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