import java.util.*;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        long low = sc.nextLong();
        long high = sc.nextLong();
        long maxNumber = high / 2 * 2;
        for (long i = (long)(Math.sqrt(high)); i >= 3 ; i--) {
            if (!isPrime(i)) {
                continue;
            }
            for (long j = high / i * i; j >= low; j -= i) {
                if (getMax(j) >= i) {
                    System.out.println(j);
                    return;
                }
            }
        }
        System.out.println(maxNumber);
    }
    
    static long getMax(long x) {
        for (long i = 2; i <= Math.sqrt(x); i++) {
            if (x % i == 0) {
                return i;
            }
        }
        return x;
    }
    
    static boolean isPrime(long x) {
        for (long i = 2; i <= Math.sqrt(x); i++) {
            if (x % i == 0) {
                return false;
            }
        }
        return true;
    }
}