from collections import Counter
N=int(input())
Alist=list(map(int,input().split()))
count=Counter(Alist)
flag=True
for value in count.values():
    if value>1:
        flag=False
print('YES' if flag else 'NO') from collections import Counter N=int(input()) N int(input()) int input() input Alist=list(map(int,input().split())) Alist list(map(int,input().split())) list map(int,input().split()) map int input().split() ().split () input split count=Counter(Alist) count Counter(Alist) Counter Alist flag=True flag True for value in count.values():
    if value>1:
        flag=False value count.values() count.values count values if value>1:
        flag=False value>1 value 1 flag=False flag False print('YES' if flag else 'NO') print 'YES' if flag else 'NO' flag 'YES' 'NO' N=int(input()) int(input()) N count=Counter(Alist) Counter(Alist) count flag=True True flag Alist=list(map(int,input().split())) list(map(int,input().split())) Alist flag=False False flag
from collections import Counter
N=int(input())
Alist=list(map(int,input().split()))
count=Counter(Alist)
flag=True
for value in count.values():
    if value>1:
        flag=False
print('YES' if flag else 'NO')