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 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(); } }