from fractions import gcd
import sys

a, b = sys.stdin.readline().split()
a = int(a)
b = int(b)
if a < b:
	a, b = b, a
m = a*b
j = 0
for i in range(a-b):
	l = (a+i)*(b+i)/gcd(a+i, b+i)
	if l < m:
		m = l
		j = i
print j