A, B = [int(i) for i in input().split()]
print(max(0, A-2*B)) int(i) for i in input().split() for i in input().split() i input().split() ().split () input split for i in input().split() int(i) int i A, B = [int(i) for i in input().split()] A [int(i) for i in input().split()] B print(max(0, A-2*B)) print max(0, A-2*B) max 0 A-2*B A 2*B 2 B A, B = [int(i) for i in input().split()] [int(i) for i in input().split()] A B = [int(i) for i in input().split()] [int(i) for i in input().split()] B
A, B = [int(i) for i in input().split()]
print(max(0, A-2*B))
