import java.util.Scanner;

public class Main {

    public static boolean simple(int x){
        for(int i = 2; i <= Math.sqrt(x); ++i){
            if(x % i == 0){
                return false;
            }
        }

        return true;
    }

    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        int a = in.nextInt();

        while(true){
            a++;
            if(simple(a)){
                System.out.println(a);
                return;
            }
        }

    }
}