foo.cc: In function 'int main()':
foo.cc:11:20: 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 < s.length(); i++)
      |                  ~~^~~~~~~~~~~~
foo.cc:18:52: error: 'n' was not declared in this scope
   18 |  cout << fixed << setprecision(2) << double(cnt) / n * 100 << "%" << endl;
      |                                                    ^

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