import java.util.Arrays;
import java.util.Scanner;
public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int num = sc.nextInt();
        int[] arr = new int[num];
        int count = 0;
        for (int i = 0; i < arr.length; i++) {
            arr[i] = (int) (1 + Math.random() * 999);
        }
        Arrays.sort(arr);
        for (int i = 0; i < arr.length - 1; i++) {
            for (int j = i + 1; j < arr.length; j++) {
                if (arr[i] == arr[j]) {
                    arr[j] = 0;
                }
            }
        }
        for (int i = 0; i < arr.length; i++) {
            if (arr[i] != 0) {
                count++;
            }
        }
        System.out.println(count);
        for (int i = 0; i < arr.length; i++) {
            if (arr[i] != 0) {
                System.out.print(arr[i] + " ");
            }
        }
    }
}