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