import java.util.*;

public class MissingNumberSimple {
    public static void main(String[] args) {
        Scanner s= new Scanner(System.in);
        int n = s.nextInt();
        if (n < 0) {
            System.out.println("Invalid input");
            return;
        }

        int[] nums = new int[n];
        for (int i = 0; i < n; i++) {
            nums[i] = sc.nextInt();
        }
        for (int i = 1; ; i++) {
            boolean found = false;
            for (int j = 0; j < n; j++) {
                if (nums[j] == i) {
                    found = true;
                    break;
                }
            }
            if (!found) {
                System.out.println(i);
                break;
            }
        }
    }
}