import java.io.BufferedReader;
import java.io.InputStreamReader;

public class Main {
	public static void main(String[] args) throws Exception {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		int n = Integer.parseInt(br.readLine());
		String[] sa = br.readLine().split(" ");
		int[] a = new int[n];
		for (int i = 0; i < n; i++) {
			a[i] = Integer.parseInt(sa[i]);
		}
		br.close();

		int min = 1000000007;
		for (int i = 0; i < n; i++) {
			min = Math.min(min, a[i]);
		}
		if (min <= 1) {
			System.out.println("Yes");
		} else {
			System.out.println("No");
		}
	}
}