def main():
	n = int(input())
	k = int(input())
	arr = [int(input()) for _ in range (n)]
	
	mp = {}
	for i in range(n):
		if arr[i] in mp and i-mp[arr[i]]<=k:
			print('yes')
			return
		mp[arr[i]]= i
	print('no')
	return
	
if __name__=="__main__":
	main()