from sys import stdin
input = stdin.readline


def main():
  N = int(input())
  A = list(map(int, input().split()))

  print('YES' if N == len(set(A)) else 'NO')


if(__name__ == '__main__'):
  main() from sys import stdin input = stdin.readline input stdin.readline stdin readline def main():
  N = int(input())
  A = list(map(int, input().split()))

  print('YES' if N == len(set(A)) else 'NO') main N = int(input()) N int(input()) int input() input A = list(map(int, input().split())) A list(map(int, input().split())) list map(int, input().split()) map int input().split() ().split () input split print('YES' if N == len(set(A)) else 'NO') print 'YES' if N == len(set(A)) else 'NO' N == len(set(A)) N len(set(A)) len set(A) set A 'YES' 'NO' if(__name__ == '__main__'):
  main() __name__ == '__main__' __name__ '__main__' main() main def main():
  N = int(input())
  A = list(map(int, input().split()))

  print('YES' if N == len(set(A)) else 'NO') def main():
  N = int(input())
  A = list(map(int, input().split()))

  print('YES' if N == len(set(A)) else 'NO') main input = stdin.readline stdin.readline input
from sys import stdin
input = stdin.readline


def main():
  N = int(input())
  A = list(map(int, input().split()))

  print('YES' if N == len(set(A)) else 'NO')


if(__name__ == '__main__'):
  main()
