[Enter 2 integers on 1 line.
  Use whitespace to separate. Example: 2 3
  Use underscore for negative integers. Example: _10
]P ? sb sa
[add: ]P la lb + p sz
[sub: ]P la lb - p sz
[mul: ]P la lb * p sz
[div: ]P la lb / p sz  [truncates toward zero]sz
[mod: ]P la lb % p sz  [sign matches first operand]sz
[pow: ]P la lb ^ p sz