#include <bits/stdc++.h>
//#include <atcoder/all>
using namespace std;
//using namespace atcoder;
//using mint = modint1000000007;
//const int mod = 1000000007;
//using mint = modint998244353;
//const int mod = 998244353;
//const int INF = 1e9;
//const long long LINF = 1e18;
#define rep(i, n) for (int i = 0; i < (n); ++i)
#define rep2(i,l,r)for(int i=(l);i<(r);++i)
#define rrep(i, n) for (int i = (n-1); i >= 0; --i)
#define rrep2(i,l,r)for(int i=(r-1);i>=(l);--i)
#define all(x) (x).begin(),(x).end()
#define allR(x) (x).rbegin(),(x).rend()
#define endl "\n"
#define P pair<int,int>
template<typename A, typename B> inline bool chmax(A & a, const B & b) { if (a < b) { a = b; return true; } return false; }
template<typename A, typename B> inline bool chmin(A & a, const B & b) { if (a > b) { a = b; return true; } return false; }
// 素因数分解
vector<pair<long long, int>> PrimeFactorization(long long n) {
	vector<pair<long long, int>> ret;
	for (long long i = 2; i*i <= n; i++) {
		int c = 0;
		while (n%i == 0) { // 素数で割り切れなくなるまで割っていく
			c++;//割った個数を配列に足す
			n /= i;
		}
		if (0 != c) ret.push_back({ i,c });
		if (1 == n) break;
	}
	if (1 != n) ret.push_back({ n,1 });
	return ret;
}
int main() {
	ios::sync_with_stdio(false);
	cin.tie(nullptr);
	int n, k; cin >> n >> k;
	auto v = PrimeFactorization(n);
	vector<int>cnt(n + 1);
	rep(i, v.size())cnt[v[i].first] = v[i].second;
	P ans = { 0,0 };
	rep2(i, 1, n) {
		auto v = PrimeFactorization(i);
		int x = 0;
		int y = 1;
		rep(j, v.size()) {
			x += min(cnt[v[j].first], v[j].second);
			y *= v[j].second + 1;
		}
		if (x < k) continue;
		if (chmax(ans.second, y)) ans.first = i;
	}
	cout << ans.first << endl;
	return 0;
}