if __name__ == '__main__':

	n = int(input())
	s = set(input().split())

	if len(s) == n:
		print("YES")
	else:
		print("NO") if __name__ == '__main__':

	n = int(input())
	s = set(input().split())

	if len(s) == n:
		print("YES")
	else:
		print("NO") __name__ == '__main__' __name__ '__main__' n = int(input()) n int(input()) int input() input s = set(input().split()) s set(input().split()) set input().split() ().split () input split if len(s) == n:
		print("YES")
	else:
		print("NO") len(s) == n len(s) len s n print("YES") print "YES" print("NO") print "NO" n = int(input()) int(input()) n s = set(input().split()) set(input().split()) s
if __name__ == '__main__':

	n = int(input())
	s = set(input().split())

	if len(s) == n:
		print("YES")
	else:
		print("NO")
