foo.cc: In function 'int main()':
foo.cc:10:18: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   10 |     for(int i=1;i<=s1.size();i++)
      |                 ~^~~~~~~~~~~
foo.cc:12:18: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   12 |     for(int j=1;j<=s2.size();j++)
      |                 ~^~~~~~~~~~~

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