/in/foo.cc: In function 'long long int apply_op(long long int, long long int, char)':
/in/foo.cc:42:9: error: jump to case label
   42 |         default: return 0;
      |         ^~~~~~~
/in/foo.cc:39:23: note:   crosses initialization of 'long long int res'
   39 |             long long res = 1;
      |                       ^~~
/in/foo.cc:44:1: warning: control reaches end of non-void function [-Wreturn-type]
   44 | }
      | ^