def main():
    n = int(input())
    a_list = list(map(int, input().split()))
    a_set = set(a_list)

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


if __name__ == "__main__":
    main() def main():
    n = int(input())
    a_list = list(map(int, input().split()))
    a_set = set(a_list)

    if len(a_set) == n:
        print("YES")
    else:
        print("NO") main n = int(input()) n int(input()) int input() input a_list = list(map(int, input().split())) a_list list(map(int, input().split())) list map(int, input().split()) map int input().split() ().split () input split a_set = set(a_list) a_set set(a_list) set a_list if len(a_set) == n:
        print("YES")
    else:
        print("NO") len(a_set) == n len(a_set) len a_set n print("YES") print "YES" print("NO") print "NO" if __name__ == "__main__":
    main() __name__ == "__main__" __name__ "__main__" main() main def main():
    n = int(input())
    a_list = list(map(int, input().split()))
    a_set = set(a_list)

    if len(a_set) == n:
        print("YES")
    else:
        print("NO") def main():
    n = int(input())
    a_list = list(map(int, input().split()))
    a_set = set(a_list)

    if len(a_set) == n:
        print("YES")
    else:
        print("NO") main
def main():
    n = int(input())
    a_list = list(map(int, input().split()))
    a_set = set(a_list)

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


if __name__ == "__main__":
    main()
