# No.333 門松列を数え上げ
a, b = [int(i) for i in input().split()]

if a < b:
    print((a - 1) + (b - a - 1))
elif a == 2000000000:
    print(2000000000 - a - 1)
else:
    print((2000000000 - a - 1) + (a - b))