#include <iostream>
#include <map>
#include <vector>
using namespace std;
typedef pair<int,int> P;
int N,K;
map<int,int> m;


int main(){
    cin >> N >> K;
    int n = N;
    for(int i=2;i*i<=N;i++){
        while(n%i==0){
            n /= i;
            m[i]++;
        }
    }
    if(n!=1) m[n]++;
    int ans = 1e9,ma = 0;
    for(int i=2;i<N;i++){
        int n2 = i;
        map<int,int> m2;
        for(int j=2;j*j<=n2;j++){
            while(n2%j==0){
                n2 /= j;
                m2[j]++;
            }   
        }
        if(n2!=1) m2[n2]++;
        int num = 1,cnt = 0;
        for(auto x:m2){
            num *= x.second+1;
            if(m.count(x.first)) cnt += min(m[x.first],x.second);
        }
        //cerr << i << " " << num << " " << cnt << endl;
        if(cnt<K) continue;
        if(ma<num) ans = i;
        if(ma==num) ans = min(ans,i);
        ma = max(ma,num);
    }
    cout << ans << endl;
}