n=int(input())
a=[int(i) for i in input().split()]
if(len(set(a))==n):
    print('YES')
else:
    print('NO') n=int(input()) n int(input()) int input() input int(i) for i in input().split() for i in input().split() i input().split() ().split () input split for i in input().split() int(i) int i a=[int(i) for i in input().split()] a [int(i) for i in input().split()] if(len(set(a))==n):
    print('YES')
else:
    print('NO') len(set(a))==n len(set(a)) len set(a) set a n print('YES') print 'YES' print('NO') print 'NO' a=[int(i) for i in input().split()] [int(i) for i in input().split()] a n=int(input()) int(input()) n
n=int(input())
a=[int(i) for i in input().split()]
if(len(set(a))==n):
    print('YES')
else:
    print('NO')