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

#define int long long
#define rep(i,l,r) for(int i=(int)(l);i<(int)(r);i++)
#define all(x) (x).begin(),(x).end()
#define sz(x) ((int)x.size())
template<class T>bool chmax(T &a,T b){if(a<b){a=b;return 1;}return 0;}
template<class T>bool chmin(T &a,T b){if(a>b){a=b;return 1;}return 0;}

typedef pair<int, int> pii;
typedef vector<int> vi;
typedef vector<vi> vvi;

const int inf = 1LL<<60;
const int mod = 1e9 + 7;
const double eps = 1e-9;

/*{
  }*/

int gcd(int a, int b){
  return b ? gcd(b, a%b) : a;
}

signed main(){
  int n, k;
  cin >> n >> k;

  int ans = 0, div = 0;
  rep(i, 1, n){
    int g = gcd(n, i);

    int tmp = 0;
    rep(j, 2, g/j+1){
      int c = 0;
      while(g%j == 0){
        c++;
        g /= j;
      }
      tmp += c;
    }
    if(g != 1) tmp++;

//    cout << i << " " << tmp << endl;
    if(tmp < k) continue;

    tmp = 1;
    int t = i;
    rep(j, 2, t/j+1){
      int c = 0;
      while(t%j == 0){
        c++;
        t /= j;
      }
      tmp *= (c+1);
    }
    if(t != 1) tmp *= 2;
    
    if(chmax(div, tmp)){
      ans = i;
    }
//    cout << i << " " << tmp << " " << ans << endl;
  }

  cout << ans << endl;

  return 0;
}