foo.cc: In function 'int main()':
foo.cc:17:17: error: 'q' was not declared in this scope
   17 |  for (int i=0;i<q;i++)
      |                 ^
foo.cc:21:10: error: expected '(' before 'op'
   21 |   switch op:
      |          ^~
      |          (

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