import math
N, K = map(int, input().split())
Ints = [i for i in range(N)]
Primefactors = [0]*N
Factors = [1]*N
for i in range(2, math.floor(N)+1):
    if Ints[i] == 1:
        continue
    for j in range(1, N):
        if i*j < N:
            t = 1
            while Ints[i*j]%i == 0:
                Ints[i*j] //= i
                Primefactors[i*j] += 1
                t += 1
            Factors[i*j] *= t
        else:
            break
            
nowfactors=ans=1
for i in range(2,N):
    if Primefactors[math.gcd(i,N)] >= K:
        if Factors[i] > nowfactors:
            ans = i
            nowfactors = Factors[i]
print(ans)