foo.cc: In function 'int main()':
foo.cc:28:32: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   28 |         else for (int i = 4; i < s.size() - 1; i++)
      |                              ~~^~~~~~~~~~~~~~
foo.cc:47:43: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   47 |                         for (int i = 0; i < s1.size(); i++) {
      |                                         ~~^~~~~~~~~~~

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