#include <bits/stdc++.h>
using namespace std;

constexpr long lim = 100001;
vector<vector<int>> pr(lim), id(lim);
vector<bool> is_pr(lim, true);

void all_fac() {
  is_pr.at(0) = 0;
  is_pr.at(1) = 0;
  for (int i = 2; i < lim; i++) {
    if (is_pr.at(i)) {
      pr.at(i).push_back(i);
      id.at(i).push_back(1);
      for (int j = 2 * i; j < lim; j += i) {
        is_pr.at(j) = false;
        int cnt = 0;
        int nw = j;
        while(nw % i == 0) {
          nw /= i;
          cnt++;
        }
        pr.at(j).push_back(i);
        id.at(j).push_back(cnt);
      }
    }
  }
}

int main() {
  all_fac();
  int N, K;
  cin >> N >> K;
  int mx = 0, ans = 0;
  for (int i = 1; i < N; i++) {
    int tmp = gcd(i, N);
    int tmp2 = accumulate(id.at(tmp).begin(), id.at(tmp).end(), 0);
    if (tmp2 >= K) {
      int tmp3 = 1;
      for (auto a : id.at(i)) tmp3 *= (a + 1);
      if (tmp3 > mx) mx = tmp3, ans = i;
    }
  }
  cout << ans << "\n";
}