import sys
N = int(input())
cc = list(map(int,input().split()))
dic = set()
for i in cc:
  if i in dic:
    print('NO')
    sys.exit()
  else:
    dic.add(i)
print('YES') import sys sys N = int(input()) N int(input()) int input() input cc = list(map(int,input().split())) cc list(map(int,input().split())) list map(int,input().split()) map int input().split() ().split () input split dic = set() dic set() set for i in cc:
  if i in dic:
    print('NO')
    sys.exit()
  else:
    dic.add(i) i cc if i in dic:
    print('NO')
    sys.exit()
  else:
    dic.add(i) i in dic i dic print('NO') print 'NO' sys.exit() sys.exit sys exit dic.add(i) dic.add dic add i print('YES') print 'YES' N = int(input()) int(input()) N cc = list(map(int,input().split())) list(map(int,input().split())) cc dic = set() set() dic
import sys
N = int(input())
cc = list(map(int,input().split()))
dic = set()
for i in cc:
  if i in dic:
    print('NO')
    sys.exit()
  else:
    dic.add(i)
print('YES')