#yuki811
import math,collections

def prime_list(x):
 primes=[]
 for i in range(2,math.ceil(math.sqrt(x))+1):
  while x%i==0:
   primes.append(i)
   x//=i
 if x>1:
  primes.append(x)
 return primes

def factors(x):
 res = 1
 for v in collections.Counter(prime_list(x)).values():
  res*=v+1
 return res

n,k=map(int,input().split())
dic=collections.defaultdict(list)
for m in range(2,n):
 if len(prime_list(math.gcd(m, n)))>=k:
  dic[factors(m)].append(m)
print(min(dic[max(dic)]))