a, b = map(int, input().split())
print(0 if a - b * 2 < 0 else a - b * 2)

4b33450ebfca9dcb8fc3dd2b87ab18a293e37e4c
<mask token>

<mask token>
print(0 if a - b * 2 < 0 else a - b * 2)

a, b = map(int, input().split())
print(0 if a - b * 2 < 0 else a - b * 2)
