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

using namespace std;

#define DEBUG(x) cerr<<#x<<": "<<x<<endl;
#define DEBUG_VEC(v) cerr<<#v<<":";for(int i=0;i<v.size();i++) cerr<<" "<<v[i]; cerr<<endl
#define DEBUG_MAT(v) cerr<<#v<<endl;for(int i=0;i<v.size();i++){for(int j=0;j<v[i].size();j++) {cerr<<v[i][j]<<" ";}cerr<<endl;}


typedef long long ll;
#define vi vector<int>
#define vl vector<ll>
#define vii vector< vector<int> >
#define vll vector< vector<ll> >
#define vs vector<string>
#define pii pair<int,int>
#define pis pair<int,string>
#define psi pair<string,int>
#define pll pair<ll,ll>
template<class S, class T> pair<S, T> operator+(const pair<S, T> &s, const pair<S, T> &t) { return pair<S, T>(s.first + t.first, s.second + t.second); }
template<class S, class T> pair<S, T> operator-(const pair<S, T> &s, const pair<S, T> &t) { return pair<S, T>(s.first - t.first, s.second - t.second); }
template<class S, class T> ostream& operator<<(ostream& os, pair<S, T> p) { os << "(" << p.first << ", " << p.second << ")"; return os; }
#define X first
#define Y second
#define rep(i,n) for(int i=0;i<(n);i++)
#define rep1(i,n) for(int i=1;i<=(n);i++)
#define rrep(i,n) for(int i=(n)-1;i>=0;i--)
#define rrep1(i,n) for(int i=(n);i>0;i--)
#define REP(i,a,b) for(int i=a;i<b;i++)
#define in(x, a, b) (a <= x && x < b)
#define all(c) c.begin(),c.end()
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; }
#define UNIQUE(v) v.erase(std::unique(v.begin(), v.end()), v.end());
const ll inf = 1000000001;
const ll INF = (ll)1e18 + 1;
const ll MOD = 1000000007;
//const ll MOD = 998244353;
const double pi = 3.14159265358979323846;
#define Sp(p) cout<<setprecision(15)<< fixed<<p<<endl;
int dx[4] = { -1,0, 1,0 }, dy[4] = { 0,1,0,-1 };
int dx2[8] = { 1,1,0,-1,-1,-1,0,1 }, dy2[8] = { 0,1,1,1,0,-1,-1,-1 };
#define fio() cin.tie(0); ios::sync_with_stdio(false);
//#define mp make_pair

void prime(vector<bool> &isprime , vector<map<int, int> > &soinsu ) {
  ll i, j;
  isprime[0] = isprime[1] = false;
  for (i = 2; i < isprime.size(); i++) {
    if (isprime[i]) {
      soinsu[i][i] = 1;
      for (j = 2; i*j < isprime.size(); j++) {
        isprime[i*j] = false;
        int temp = i * j;
        while (temp % i == 0) {
          soinsu[i*j][i]++;
          temp /= i;
        }
      }
    }
  }
}


int main() {
  int n, k;
  cin >> n >> k;
  vector<bool> isprime(n + 1, true);
  vector<map<int, int> > soinsu(n + 1);
  prime(isprime, soinsu);

  int ma = 0;
  int ans = 1;
  for (int x = 2; x < n; x++) {
    int cnt = 0;
    for (auto itr = soinsu[n].begin(); itr != soinsu[n].end(); itr++) {
      int p = itr->first, m = itr->second;
      cnt += min(m, soinsu[x][p]);
    }
    if (cnt >= k) {
      ll num = 1;
      for (auto itr = soinsu[x].begin(); itr != soinsu[x].end(); itr++) {
        num *= (itr->second + 1);
      }
      if (num > ma) {
        ans = x;
        ma = num;
      }
    }
  }
  cout << ans << endl;
}