import java.io.*;
import java.util.*;

public class Main {
    public static void main(String[] args) throws Exception {
        Scanner sc = new Scanner();
        int n = sc.nextInt();
        int k = sc.nextInt();
        ArrayList<Integer> base = new ArrayList<>();
        int xx = n;
        for (int i = 2; i <= Math.sqrt(xx); i++) {
            while (xx % i == 0) {
                base.add(i);
                xx /= i;
            }
        }
        if (xx > 1) {
            base.add(xx);
        }
        int[] counts = new int[n];
        counts[1] = 1;
        int[] size = new int[n];
        for (int i = 2; i < n; i++) {
            counts[i]++;
            for (int j = 1; j * i < n; j++) {
                counts[j * i]++;
            }
            int x = i;
            for (int y : base) {
                if (x % y == 0) {
                    size[i]++;
                    x /= y;
                }
            }
        }
        int max = 0;
        int ans = 0;
        for (int i = 2; i < n; i++) {
            if (size[i] >= k && counts[i] > max) {
                max = counts[i];
                ans = i;
            }
        }
        System.out.println(ans);
    }
    
}

class Scanner {
    BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
    StringTokenizer st = new StringTokenizer("");
    
    public Scanner() throws Exception {
        
    }
    
    public int nextInt() throws Exception {
        return Integer.parseInt(next());
    }
    
    public long nextLong() throws Exception {
        return Long.parseLong(next());
    }
    
    public double nextDouble() throws Exception {
        return Double.parseDouble(next());
    }
    
    public String next() throws Exception {
        while (!st.hasMoreTokens()) {
            st = new StringTokenizer(br.readLine());
        }
        return st.nextToken();
    }
}