/in/foo.cc: In function 'int main()':
/in/foo.cc:14:27: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   14 |         for (int i = 0; i < s.length(); i++)
      |                         ~~^~~~~~~~~~~~
/in/foo.cc:18:28: warning: suggest explicit braces to avoid ambiguous 'else' [-Wdangling-else]
   18 |                         if (s[i] == ')')
      |                            ^
/in/foo.cc:44:43: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   44 |                         for (int i = 0; i < lidx.size(); i++)
      |                                         ~~^~~~~~~~~~~~~