import sys
from math import floor,ceil,sqrt
from collections import defaultdict
N,K=map(int,input().split())
def check(N):
    dd=defaultdict(int)
    M=int(sqrt(N))+3
    A=N
    for i in range(2,M):
        if A%i==0:
            num=0
            while A%i==0:
                A=A//i
                num+=1
            dd[i]=num
    if A!=1:
        dd[A]=1
    return dd
ddN=check(N)
#print(ddN)
ans=10000000
p=0
for u in range(N-1,0,-1):
    t=1
    k=0
    A=u
    for i,n in ddN.items():
        if A%i==0:
            num=0
            while A%i==0:
                A=A//i
                num+=1
            k+=min(n,num)
            t*=(num+1)
    if k<K:
        continue
    #print(A)
    dd=check(A)
    for i,n in dd.items():
        t*=(n+1)
    if p<=t:
        p=t
        ans=u
    #print(u,t,p,ans,dd)
print(ans)