n=int(eval(input()))

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

if len(a)==len(set(a)):

  print('YES')

else:

  print('NO')

def solve():

    N = int(eval(input()))

    A = set(input().split())

    

    a = len(A)

    if a == N:

        print("YES")

    elif a != N:

        print("NO")





if __name__ == '__main__':

    solve()

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

def solve():
    N = int(eval(input()))
    A = set(input().split())
    a = len(A)
    if a == N:
        print("YES")
    elif a != N:
        print("NO")


if __name__ == "__main__":
    solve()

-n = int(eval(input())) -a = list(map(int, input().split())) -if len(a) == len(set(a)): -    print("YES") -else: -    print("NO") +def solve(): +    N = int(eval(input())) +    A = set(input().split()) +    a = len(A) +    if a == N: +        print("YES") +    elif a != N: +        print("NO") + + +if __name__ == "__main__": +    solve()