#include <iostream>
#include <algorithm>
#include <vector>
#include <string>
#include <map>

using namespace std;

map<int, int> f(int n) {
  map<int, int> res;
  for (int i = 2; i <= n; i++) {
    while (n % i == 0) {
      res[i]++;
      n /= i;
    }
  }
  return res;
}

int common(int n, map<int, int> mp) {
  int res = 0;
  for (auto e : mp) {
    int c = 0;
    while (n % e.first == 0) {
      n /= e.first;
      c++;
    }
    res += min(c, e.second);
  }
  return res;
}

int main() {
  int N, K;
  cin >> N >> K;
  vector<int> d(N);
  for (int i = 1; i < N; i++) {
    for (int j = i; j < N; j += i) {
      d[j]++;
    }
  }
  auto mp = f(N);
  pair<int, int> ans;
  for (int i = 1; i < N; i++) {
    if (common(i, mp) >= K) {
      ans = max(ans, {d[i], -i});
    }
  }
  cout << -ans.second << endl;
}