// includes
#include <bits/stdc++.h>

// macros
#define ll long long int
#define pb emplace_back
#define mk make_pair
#define pq priority_queue
#define FOR(i, a, b) for(int i=(a);i<(b);++i)
#define rep(i, n) FOR(i, 0, n)
#define rrep(i, n) for(int i=((int)(n)-1);i>=0;i--)
#define all(x) (x).begin(),(x).end()
#define sz(x) ((int)(x).size())
#define UNIQUE(v) v.erase(unique(v.begin(), v.end()), v.end())
#define FI first
#define SE second
using namespace std;

//  types
typedef pair<int, int> P;
typedef pair<ll, int> Pl;
typedef pair<ll, ll> Pll;
typedef pair<double, double> Pd;
 
// constants
const int inf = 1e9;
const ll linf = 1LL << 50;
const double EPS = 1e-10;
const int mod = 1e9 + 7;

// solve
template <class T>bool chmax(T &a, const T &b){if(a < b){a = b; return 1;} return 0;}
template <class T>bool chmin(T &a, const T &b){if(a > b){a = b; return 1;} return 0;}
template <typename T> istream &operator>>(istream &is, vector<T> &vec){for(auto &v: vec)is >> v; return is;}

template <typename T>
T power(T a, T n, T mod) {
  T res = 1;
  T tmp = n;
  T curr = a;
  while(tmp){
    if(tmp % 2 == 1){
      res = (T)((ll)res * curr % mod);
    }
    curr = (T)((ll)curr * curr % mod);
    tmp >>= 1;
  }
  return res;
}

template <typename T>
bool suspect(T a, int s, T d, T n){
  T x = power<T>(a, d, n);
  if(x == 1)return true;
  for(int r = 0; r < s; r++){
    if(x == n - 1)return true;
    x = x * x % n;
  }
  return false;
}

template <typename T>
bool millar_rabin(T n){
  if(n <= 1 || (n > 2 && n % 2 == 0))return false;
  vector<ll> test = {2, 3, 5, 7, 11, 13, 17, 19, 23};
  T d = n - 1;
  int s = 0;
  while(d % 2 == 0)s++, d /= 2;
  for(int i = 0; i < test.size() && test[i] < n; i++){
    if(!suspect<T>(test[i], s, d, n))return false;
  }
  return true;
}

template <typename T>
vector<T> list_prime(T n){
  vector<T> res;
  vector<bool> i_prime = vector<bool>(n+1, true);
  for(ll i = 2; i <= n; i++){
    if(i_prime[i]){
      res.push_back(i);
      for(ll j = 2; j * i <= n; j++){
        i_prime[i * j] = false;
      }
    }
  }
  return res;
}

int main(int argc, char const* argv[])
{
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  int n, k;
  cin >> n >> k;
  auto p = list_prime(n);
  int res = 0;
  int maxi = -1;
  for(int i = 1; i < n; i++){
    int cnt = 0;
    for(int j = 0; j < sz(p) && p[j] <= i; j++){
      int itmp = i, ntmp = n;
      while(itmp % p[j] == 0 && ntmp % p[j] == 0){
        cnt++;
        itmp /= p[j];
        ntmp /= p[j];
      }
    }
    if(cnt >= k){
      int tmp = 0;
      for(int j = 2; j * j <= i; j++){
        if(i % j == 0)tmp++;
        if(i % j == 0 && j * j != i)tmp++;
      }
      if(tmp > maxi){
        maxi = tmp;
        res = i;
      }
    }
  }
  cout << res << endl;
	return 0;
}