import collections
N = int(input())
A = list(map(int, input().split()))
c = collections.Counter(A)
if c.most_common()[0][1] > 1:
    print('NO')
else:
    print('YES') import collections collections 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 = collections.Counter(A) c collections.Counter(A) collections.Counter collections Counter A if c.most_common()[0][1] > 1:
    print('NO')
else:
    print('YES') c.most_common()[0][1] > 1 c.most_common()[0][1] [0] c.most_common() c.most_common c most_common 0 1 1 print('NO') print 'NO' print('YES') print 'YES' c = collections.Counter(A) collections.Counter(A) c A = list(map(int, input().split())) list(map(int, input().split())) A N = int(input()) int(input()) N
import collections
N = int(input())
A = list(map(int, input().split()))
c = collections.Counter(A)
if c.most_common()[0][1] > 1:
    print('NO')
else:
    print('YES')