/in/foo.cc: In function 'void build_next()':
/in/foo.cc:21:26: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   21 |         for(int i = 1; i < n.length(); i++)
      |                        ~~^~~~~~~~~~~~
/in/foo.cc: In function 'int main()':
/in/foo.cc:39:33: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   39 |         for(int i = 0, j = 0; i < s.length(); i++)
      |                               ~~^~~~~~~~~~~~
/in/foo.cc:47:22: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   47 |                 if(j == n.length())
      |                    ~~^~~~~~~~~~~~~