#include "bits/stdc++.h"
#define in std::cin
#define out std::cout
#define rep(i,N) for(LL i=0;i<N;++i)
typedef long long int LL;

std::map<LL, LL> decomposit_prime(LL n)
{
	LL d = 2;
	std::map<LL, LL>res;
	while (d * d <= n)
	{
		if (n % d == 0)
		{
			++res[d];
			n /= d;
		}
		else ++d;
	}
	++res[n];
	return res;
}

std::vector<LL>divisor(LL num)
{
	std::vector<LL>res;
	for (LL i = 1; i * i <= num; ++i)
	{
		if (num % i == 0)
		{
			res.push_back(i);
			if ((num / i) != i) res.push_back(num / i);
		}
	}
	return res;
}

int main()
{
	LL N, K;
	in >> N >> K;

	auto N_primes = decomposit_prime(N);
	LL ansN, ansC = 0;
	for (LL i = 1; i < N; ++i)
	{
		auto M_primes = decomposit_prime(i);
		LL same = 0;
		for (auto j : M_primes) same += std::min(j.second, N_primes[j.first]);
		if (same < K) continue;
		auto M_divs = divisor(i);
		if (ansC < M_divs.size())
		{
			ansN = i;
			ansC = M_divs.size();
		}
	}

	out << ansN << std::endl;
}