a, b = map(int, input().split())

if a > b:
    c = (a - b - 1) + (2 * 10**9 - a)#cが真ん中＋cが右
elif a < b and b == 2 * 10**9:
    c = 2 * 10**9 - 2
elif a < b:
    c = (a - 1) + (b - a - 1)#cが左＋cが真ん中

print(c)