#include <stdio.h>

int main()
{
	int i, N, A[200001];
	scanf("%d", &N);
	for (i = 1; i <= N; i++) scanf("%d", &(A[i]));
	for (i = 1; i <= N; i++) if (A[i] <= 1) break;
	if (i <= N) printf("Yes\n");
	else printf("No\n");
	fflush(stdout);
	return 0;
}