file = open('mod.in')
data = file.read()
a=int(data[0])
b=int(data[1])
file.close()
ot=1
for i in range(max(a,b)):
if a%(i+2)==b%(i+2):
ot=i+2
break
print(ot)
file = open('mod.out','w')
file.write(ot)
file.close()
ZmlsZSA9IG9wZW4oJ21vZC5pbicpCmRhdGEgPSBmaWxlLnJlYWQoKQoKYT1pbnQoZGF0YVswXSkKYj1pbnQoZGF0YVsxXSkKZmlsZS5jbG9zZSgpCm90PTEKZm9yIGkgaW4gcmFuZ2UobWF4KGEsYikpOgoJaWYgYSUoaSsyKT09YiUoaSsyKToKCQlvdD1pKzIKCQlicmVhawoKcHJpbnQob3QpCmZpbGUgPSBvcGVuKCdtb2Qub3V0JywndycpCmZpbGUud3JpdGUob3QpCmZpbGUuY2xvc2UoKQo=