import java.util.Scanner;

public class CheckZeroOrOne {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        int n = scanner.nextInt();
        int[] A = new int[n];
        boolean containsZeroOrOne = false;
        for (int i = 0; i < n; i++) {
            A[i] = scanner.nextInt();
            if (A[i] == 0 || A[i] == 1) {
                containsZeroOrOne = true;
            }
        }
        if (containsZeroOrOne) {
            System.out.println("Yes");
        } else {
            System.out.println("No");
        }
        scanner.close();
    }
}