foo.cc: In function 'std::string remove(std::string, char)':
foo.cc:22:22: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   22 |     for (int i = 0;i < in.length();i++)
      |                    ~~^~~~~~~~~~~~~

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