import java.io.BufferedReader;
import java.io.InputStreamReader;

public class No192 {

    public static void main(String[] args) {
        try {
            BufferedReader br = new BufferedReader(new InputStreamReader(
                    System.in));
            int N = Integer.parseInt(br.readLine());
            for (int i = N - 100; i < N + 100; i++) {

                if (i < 2) {
                    i = 1;
                    continue;
                }

                if (!isPrime(i)) {
                    System.out.println(i);
                    break;
                }
            }
        } catch (Exception e) {
            System.err.println("Error:" + e.getMessage());
        }

    }

    static boolean isPrime(long n) {

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

    }

}