/in/foo.cc: In function 'int main()':
/in/foo.cc:4:14: warning: unused variable 'ok' [-Wunused-variable]
    4 |         bool ok;
      |              ^~
/in/foo.cc:5:14: warning: unused variable 'ch' [-Wunused-variable]
    5 |         char ch;
      |              ^~