def gcd(a, b):
    while b:      
        a, b = b, a % b
    return a

def lcm(a, b):
    return a * b // gcd(a, b)

a, b = sorted(map(int, raw_input().split()))
if(a == b or a == 0):
    print 1
elif(a == 1 or (a < b-a)): 
    n = (b-a) % a
    an = a + n
    bn = b + n
    if(bn % an == 0):
        print n
        break
    else:
        n = 1
        while n < b:
            an = a + n
            bn = b + n
            if(bn % an == 0):
                print n
                break
            n = n + 1
else:
    print b-a - a%(b-a)