/in/foo.cc: In function 'int main()':
/in/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=0; i<input.length(); ++i) {
      |                 ~^~~~~~~~~~~~~~~
/in/foo.cc:4:6: warning: unused variable 'n' [-Wunused-variable]
    4 |  int n=0;
      |      ^