import java.util.*;

public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);

		int N = sc.nextInt(), flag = 0, cnt = 0;
		
		for(int i = N - 100; i <= N + 100; i++) {
			if(i <= 1)	flag = 1;
			if(i == 2)	flag = 1;
			if(flag == 0) {
				for(int j = 2; j < i; j++) {
					if(i % j == 0) {
						flag = 1;
						break;
					}
				}
				if(flag == 1) {
					flag = 0;
				} else {
					flag = 1;
				}
			}
			if(flag == 0) {
				System.out.println(i);
				break;
			}
			
			flag = 0;
		}
	}
}