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

public class Main {
    public static void main(String[] args) throws Exception {
        Scanner sc = new Scanner();
        int n = sc.nextInt();
        int k = sc.nextInt();
        int[] counts = new int[n + 1];
        int[] count2 = new int[n + 1];
        int[] values = new int[n + 1];
        for (int i = 2; i <= n; i++) {
            values[i] = i;
        }
        for (int i = 1; i <= n; i++) {
            for (int j = 1; j * i <= n; j++) {
                counts[j * i]++;
                if (j > 1 && values[i] == i) {
                    while (values[j * i] % values[i] == 0) {
                        count2[j * i]++;
                        values[j * i] /= values[i];
                    }
                }
                if (values[i] == i) {
                    count2[i]++;
                }
            }
        }
        int ans = 0;
        int max = 0;
        for (int i = 2; i < n; i++) {
            if (max < counts[i]) {
                if (count2[getGCD(n, i)] >= k) {
                    max = counts[i];
                    ans = i;
                }
            }
        }
        System.out.println(ans);
    }
    
    static int getGCD(int x, int y) {
        if (y == 0) {
            return x;
        } else {
            return getGCD(y, x % y);
        }
    }
}
class Utilities {
    static String arrayToLineString(Object[] arr) {
        return Arrays.stream(arr).map(x -> x.toString()).collect(Collectors.joining("\n"));
    }
    
    static String arrayToLineString(int[] arr) {
        return String.join("\n", Arrays.stream(arr).mapToObj(String::valueOf).toArray(String[]::new));
    }
}
class Scanner {
    BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
    StringTokenizer st = new StringTokenizer("");
    StringBuilder sb = new StringBuilder();
    
    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 int[] nextIntArray() throws Exception {
        return Stream.of(br.readLine().split(" ")).mapToInt(Integer::parseInt).toArray();
    }
    
    public String next() throws Exception {
        while (!st.hasMoreTokens()) {
            st = new StringTokenizer(br.readLine());
        }
        return st.nextToken();
    }
    
}