// includes {{{
#include<iostream>
#include<iomanip>
#include<algorithm>
#include<vector>
#include<stack>
#include<queue>
#include<map>
#include<set>
#include<tuple>
#include<cmath>
#include<random>
#include<cassert>
#include<bitset>
#include<cstdlib>
// #include<deque>
// #include<multiset>
// #include<cstring>
// #include<bits/stdc++.h>
// }}}
using namespace std;
using ll = long long;

// O(N^.5)
/// --- primeFactors {{{ ///
#include <map>
map< ll, int > primeFactors(ll n) {
  map< ll, int > res;
  for(ll i = 2; i * i <= n; i++) {
    while(n % i == 0) n /= i, res[i]++;
  }
  if(n != 1) res[n] = 1;
  return res;
}
/// }}}--- ///

int popcount(int x) {
  x = (x & 0x55555555) + ((x & 0xAAAAAAAA) >> 1);
  x = (x & 0x33333333) + ((x & 0xCCCCCCCC) >> 2);
  x = (x & 0x0F0F0F0F) + ((x & 0xF0F0F0F0) >> 4);
  x = (x & 0x00FF00FF) + ((x & 0xFF00FF00) >> 8);
  x = (x & 0x0000FFFF) + ((x & 0xFFFF0000) >> 16);
  return x;
}


int main() {
  std::ios::sync_with_stdio(false), std::cin.tie(0);
  int n, k;
  cin >> n >> k;
  auto pf = primeFactors(n);
  multiset<int> v;
  for(auto p : pf) {
    while(p.second--) v.insert(p.first);
  }

  pair<int, int> best(-10, 0);

  for(int i = 1; i < n; i++) {
    auto pf = primeFactors(i);
    multiset<int> w;
    int num = 1;
    for(auto p : pf) {
      num *= p.second + 1;
      while(p.second--) w.insert(p.first);
    }
    vector<int> z;
    set_intersection(begin(v), end(v), begin(w), end(w), inserter(z, end(z)));
    if(z.size() >= k) {
      best = max(best, make_pair(num, -i));
    }
  }
  cout << -best.second << endl;

  return 0;
}