Counting Crows

Riddle: If there are fifteen crows on a fence and the farmer shoots a third of them, how many crows are left?

Answer: None. The rest of the crows flew away when they heard the gunshot.

Source: https://www.riddles.com/430

If there are fifteen crows on a fence and the farmer shoots a third of them, how many crows are left? — Counting Crows by Anonymous v1.

Riddle: If there are fifteen crows on a fence and the farmer shoots a third of them, how many crows are left? Answer: None. The rest of the crows flew away when they heard the gunshot. — by Anonymous v2.