/in/foo.cc: In function 'int main()':
/in/foo.cc:9:17: error: 'k' was not declared in this scope
    9 |                 k=n%10;
      |                 ^
/in/foo.cc:11:25: error: 'ok' was not declared in this scope
   11 |                         ok=1;
      |                         ^~