output_description: If the elements of the sequence are pairwise distinct, print `YES`; otherwise,
  print `NO`.
  
  * * *
input_description: Input is given from Standard Input in the following format:
  
      
      
      N
      A_1 ... A_N
attempt: print("YNEOS"[int(input()) > len(set(input().split())) :: 2])
  
problem_description: Statement
  
  Given is a sequence of integers A_1, A_2, ..., A_N. If its elements are
  pairwise distinct, print `YES`; otherwise, print `NO`.
samples: [{"input": "5\n    2 6 1 4 5", "output": "YES\n    \n\nThe elements are pairwise distinct.\n\n* * *"}, {"input": "6\n    4 1 3 1 6 2", "output": "NO\n    \n\nThe second and fourth elements are identical.\n\n* * *"}, {"input": "2\n    10000000 10000000", "output": "NO"}]