proc main(): cint =
  a + b
  a - b
  (a * b)
  a / b
  a mod b
  a shr b
  a shl b
  a and b
  a or b
  a xor b
  a < b
  a > b
  a <= b
  a >= b
  a == b
  a != b
  (a and b)
  a or b