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


public class Main_yukicoder371 {

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        Printer pr = new Printer(System.out);

		long l = sc.nextLong();
		long h = sc.nextLong();

		Prime prime = new Prime((int)Math.sqrt(h));
		List<Integer> primes = prime.getPrimeList();

		for (int i = primes.size() - 1; i >= 0; i--) {
			int p = primes.get(i);

			for (long j = h / p; j * p >= l; j--) {
				if (j < p) {
					break;
				}
				boolean flag = true;
				for (long e : primes) {
					if (e >= p) {
						break;
					}
					if (e * e > j) {
						break;
					}
					if (j % e == 0) {
						flag = false;
						break;
					}
				}

				if (flag) {
					pr.println(j * p);

					sc.close();
					pr.close();
					return;
				}
			}
		}

        pr.close();
        sc.close();
    }

	@SuppressWarnings("unused")
	private static class Prime {
		private int n;
		private List<Integer> primes;
		private BitSet p;

		Prime(int n) {
			this.n = n;

			p = new BitSet(n / 2);
			int m = (int)Math.sqrt(n);

			for (int i = 1; i <= m; i++) {
				if (p.get(i - 1)) {
					continue;
				}

				for (int j = 2 * i * (i + 1); 2 * j + 1 <= n; j += 2 * i + 1) {
					p.set(j - 1);
				}
			}
		}

		boolean isPrime(int n) {
			if (n == 2) {
				return true;
			}

			if (n == 1 || (n & 0x1) == 0) {
				return false;
			}

			return !p.get(n / 2 - 1);
		}

		List<Integer> getPrimeList() {
			if (primes != null) {
				return primes;
			}

			primes = new ArrayList<>();
			primes.add(2);
			for (int i = 1; 2 * i + 1 <= n; i++) {
				if (!p.get(i - 1)) {
					primes.add(2 * i + 1);
				}
			}

			return primes;
		}

		private static boolean isPrime(long n) {
			if (n == 2) {
				return true;
			}

			if (n == 1 || (n & 0x1) == 0) {
				return false;
			}

			for (long i = 3; i * i <= n; i += 2) {
				if (n % i == 0) {
					return false;
				}
			}

			return true;
		}
	}

	@SuppressWarnings("unused")
	private static class Scanner {
		BufferedReader br;
		Iterator<String> it;

		Scanner (InputStream in) {
			br = new BufferedReader(new InputStreamReader(in));
		}

		String next() throws RuntimeException  {
			try {
				if (it == null || !it.hasNext()) {
					it = Arrays.asList(br.readLine().split(" ")).iterator();
				}
				return it.next();
			} catch (IOException e) {
				throw new IllegalStateException();
			}
		}

		int nextInt() throws RuntimeException {
			return Integer.parseInt(next());
		}

		long nextLong() throws RuntimeException {
			return Long.parseLong(next());
		}

		float nextFloat() throws RuntimeException {
			return Float.parseFloat(next());
		}

		double nextDouble() throws RuntimeException {
			return Double.parseDouble(next());
		}

		void close() {
			try {
				br.close();
			} catch (IOException e) {
//				throw new IllegalStateException();
			}
		}
	}

	private static class Printer extends PrintWriter {
		Printer(PrintStream out) {
			super(out);
		}
	}
}