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

int sotbl[100010] = {};
vector<int> so;

int main(){
    int n, k;
    cin >> n >> k;

    for(int i = 2;i*i <= n;i++){
        if(sotbl[i] == 0){
            so.push_back(i);
            for(int j = i*2;j <= n;j+=i){
                sotbl[j] = 1;
            }
        }
    }

    int i = 0;
    vector<int> soin;
    int nn = n;
    while(n > 1){
        if(n % so[i] == 0){
            soin.push_back(so[i]);
            n /= so[i];
        }else{
            i++;
            if(i == so.size()){
                soin.push_back(n);
                break;
            }
        }
    }

    int ans = 0;
    int ans_yaku = 0;

    for(int i = 2;i < nn;i++){
        vector<int> sonum;
        int j = 0;
        n = i;
        while(n > 1){
            if(n % so[j] == 0){
                sonum.push_back(so[j]);
                n /= so[j];
            }else{
                j++;
                if(j == so.size()){
                    sonum.push_back(n);
                    break;
                }
            }
        }


        int cnt = 0;
        int x = 0, y = 0;
        while(x < soin.size() && y < sonum.size()){
            if(soin[x] == sonum[y]){
                cnt++;
                x++;
                y++;
            }else if(soin[x] > sonum[y]){
                y++;
            }else{
                x++;
            }
        }

        if(cnt >= k){
            int tmp = 0;
            int tcnt = 0;
            int tans = 1;
            for(int i = 0;i < sonum.size();i++){
                if(tmp != sonum[i]){
                    tans *= tcnt+1;
                    tcnt = 1;
                    tmp = sonum[i];
                }else{
                    tcnt++;
                }
            }

            tans = (tans*(tcnt+1))-1;
            if(tans > ans_yaku){
                ans = i;
                ans_yaku = tans;
            }
        }
    }

    cout << ans << endl;

    return 0;
}