n = int(eval(input()))

s = set(map(int,input().split()))

ans = "YES" if n == len(s) else "NO"

print(ans)

def main():

    n = int(eval(input()))

    a = list(map(int,input().split()))

    s = set(a)

    if n == len(s):

        print("YES")

    else:

        print("NO")



if __name__ == '__main__':

    main()
n = int(eval(input()))
s = set(map(int, input().split()))
ans = "YES" if n == len(s) else "NO"
print(ans)

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


if __name__ == "__main__":
    main()

-n = int(eval(input())) -s = set(map(int, input().split())) -ans = "YES" if n == len(s) else "NO" -print(ans) +def main(): +    n = int(eval(input())) +    a = list(map(int, input().split())) +    s = set(a) +    if n == len(s): +        print("YES") +    else: +        print("NO") + + +if __name__ == "__main__": +    main()