N = eval(input())

A = input().split()



_A = set(A)



if len(A) == len(_A):

    print('YES')

else:

    print('NO')

def main():

    N = eval(input())

    A = input().split()



    _A = set(A)



    if len(A) == len(_A):

        print('YES')

    else:

        print('NO')



if __name__ == '__main__':

    main()

N = eval(input())
A = input().split()
_A = set(A)
if len(A) == len(_A):
    print("YES")
else:
    print("NO")

def main():
    N = eval(input())
    A = input().split()
    _A = set(A)
    if len(A) == len(_A):
        print("YES")
    else:
        print("NO")


if __name__ == "__main__":
    main()

-N = eval(input()) -A = input().split() -_A = set(A) -if len(A) == len(_A): -    print("YES") -else: -    print("NO") +def main(): +    N = eval(input()) +    A = input().split() +    _A = set(A) +    if len(A) == len(_A): +        print("YES") +    else: +        print("NO") + + +if __name__ == "__main__": +    main()