#include <bits/stdc++.h>

using namespace std;

map< int, int > prime_factor(int n) {
  map< int, int > ret;
  for(int64_t i = 2; i * i <= n; i++) {
    while(n % i == 0) {
      ret[i]++;
      n /= i;
    }
  }
  if(n != 1) ret[n] = 1;
  return ret;
}
int main(){
    int N;cin >> N;int K;cin >> K;
    map<int,int> mp = prime_factor(N);
    int yaku = 0;
    int ans = 1e9;
    for(int a = 2;a < N;a++){
        map<int,int> uku = prime_factor(a);
        int cnt = 0;
        for(auto b: uku){
            cnt += min(b.second,mp[b.first]);
        }
        if(cnt >= K){
            int w = 0;
            for(int b = 1;b <= sqrt(a);b++){
                if(b*b == a)w+=1;
                else if(a%b == 0)w+=2;
            }
           // cout<<a<<" "<<w<<endl;
            if(yaku < w){
                yaku = w;
                ans = a;
            }
        }
    }
    cout<<ans<<endl;
}