You're a computer security expert (i.e a hacker who doesn't break law). Your neighbour is infamous professor MacGoofy himself. He specializes in designing programming languages and programming languages that he designs are frequently controversial for his strange design choices. This time MacGoofy needs your help A.S.A.P.! You get an emergency phone call from MacGoofy, a robot on which MacGoofy tried his new programming language Romalog is trying its best to kill him right now! MacGoofy barricaded his room, but it won't stop the robot for very long.
MacGoofy gives you the password to distantly access the code of robot but warns you that with this access level you can change the value of only one integer variable and that you have only one attempt. He also mentions, that any integer variable can be equal to an integer that has its absolute value less or equal to 3999 and if you enter anything else (like a letter or a fraction, 40000, etc), then your input will be rejected and the code won't be changed (i.e. you will waste your only attempt). You also can't "freeze" the robot by giving him too big numbers to compute, it has a quantum-optical processor that can quickly process any computations that result in a number that is less than googol by the power of googol.
You quickly load your computer and then find the suspicious while-cycle that keeps the robot active for some reason. Maybe if it will break out of this cycle the robot will stop? Here is the condition of this cycle:
Right before the cycle, there is a declaration of type and assignment of value of variable Z:
VARIABLE Z: INTEGER Z=13
So this part of code looks like this:
VARIABLE Z: INTEGER
Remember, you can only change value assigned to only one integer variable to stop the robot. And you have only one try.
You need three little insights to solve this puzzle