foo.cc: In function 'int main()':
foo.cc:11:18: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   11 |     for(int i=0;i<str.size();i++)
      |                 ~^~~~~~~~~~~
foo.cc:13:15: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   13 |         if (i == str.size() - 1)
      |             ~~^~~~~~~~~~~~~~~~~
foo.cc:10:9: warning: unused variable 'k' [-Wunused-variable]
   10 |     int k = 0;
      |         ^

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