from math import sqrt
L,H = map(int,raw_input().split())
comp = set()
ub = int(sqrt(H))+1
ans = 4
for p in xrange(2,ub):
	if p in comp:
		continue
	for c in xrange(p*2,H+1,p):
		if c in comp:
			continue
		comp.add(c)
		if c >= L:
			ans = c
print ans