https://www.acmicpc.net/problem/2960
n,k=map(int, input().split())
mlist=[i for i in range(2, n+1)]
nums=[]
while len(mlist)!=0:
p=min(mlist)
nums.append(p)
mlist.remove(p)
for m in mlist:
if m%p==0:
nums.append(m)
mlist.remove(m)
print(nums[k-1])
N, K = map(int, input().split())
tmp = 0
nums = [True] * (N + 1)
for i in range(2, N + 1):
for j in range(i, N + 1, i): # i의 배수이므로 i부터 i씩 건너뜀
if nums[j] != False:
nums[j] = False
tmp += 1
if tmp == K:
print(j)