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

#define lint long long
#define P pair<int, int>
#define LLP pair<long long, long long>
#define REP(i, x, n) for(int i = (x), i##_len = (int)(n) ; i < i##_len ; ++i)
#define rep(i, n) for(int i = 0, i##_len = (int)(n) ; i < i##_len ; ++i)
#define reps(i, n) for(int i = 1, i##_len = (int)(n) ; i <= i##_len ; ++i)
#define rrep(i, n) for(int i = (int)(n) - 1 ; i >= 0 ; --i)
#define rreps(i, n) for(int i = (int)(n) ; i > 0 ; --i)
#define SORT(x) sort((x).begin(), (x).end())
#define SORT_INV(x) sort((x).rbegin(), (x).rend())

const int IINF = (1 << 30) - 1;
const long long LLINF = 1LL << 61;
const long long MOD = 1000000007LL;
const int dx4[] = {1, 0, -1, 0}, dy4[] = {0, 1, 0, -1};
const int dx8[] = {1, 1, 0, -1, -1, -1, 0, 1}, dy8[] = {0, -1, -1, -1, 0, 1, 1, 1};
const double EPS = 1e-8;

bool comp(P &a, P &b){
    return a.second == b.second ? a.first < b.first : a.second > b.second;
}

int main(){
    cin.tie(0);
    ios::sync_with_stdio(false);

    int n, k;
    cin >> n >> k;

    vector< P > v;
    int m = n;
    for(int i = 2 ; i * i <= m ; ++i){
        if(m % i == 0){
            int cnt = 0;
            while(m % i == 0){
                m /= i;
                ++cnt;
            }
            v.emplace_back(i, cnt);
        }
    }
    if(m > 1){
        v.emplace_back(m, 1);
    }
    int siz = v.size();

    vector< P > t;
    REP(i, 2, n){
        int now = i, cnt = 0;
        rep(j, siz){
            if(v[j].first > now){
                break;
            }
            int tmp = 0;
            while(now % v[j].first == 0 && tmp < v[j].second){
                now /= v[j].first;
                ++tmp;
            }
            cnt += tmp;
        }
        if(cnt < k){
            continue;
        }
        cnt = 0;
        for(int j = 1 ; j * j <= i ; ++j){
            if(i % j == 0){
                cnt += 2;
            }
        }
        t.emplace_back(i, cnt);
    }
    sort(t.begin(), t.end(), comp);

    cout << t[0].first << endl;

    return 0;
}