foo.cc: In function 'std::string run_logic(std::string)':
foo.cc:25:27: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   25 |         for (int i = 0; i < out.length(); i++)
      |                         ~~^~~~~~~~~~~~~~
foo.cc: In function 'std::string find_bracket(int, int)':
foo.cc:63:27: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   63 |         for (int i = n; i < expression[m].length(); i++)
      |                         ~~^~~~~~~~~~~~~~~~~~~~~~~~

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