import sys
from collections import Counter
input=sys.stdin.readline

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

c=len(Counter(a))
if n==c:
  print('YES')
  
else:
  print('NO') import sys sys from collections import Counter input=sys.stdin.readline input sys.stdin.readline sys.stdin sys stdin readline 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 c=len(Counter(a)) c len(Counter(a)) len Counter(a) Counter a if n==c:
  print('YES')
  
else:
  print('NO') n==c n c print('YES') print 'YES' print('NO') print 'NO' c=len(Counter(a)) len(Counter(a)) c a=list(map(int,input().split())) list(map(int,input().split())) a input=sys.stdin.readline sys.stdin.readline input n=int(input()) int(input()) n
import sys
from collections import Counter
input=sys.stdin.readline

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

c=len(Counter(a))
if n==c:
  print('YES')
  
else:
  print('NO')