from sys import stdin
import sys
import math
from functools import reduce
import itertools

n = int(stdin.readline().rstrip())
a = [int(x) for x in stdin.readline().rstrip().split()]

if len(set(a)) == n:
    print('YES')
else:
    print('NO') from sys import stdin import sys sys import math math from functools import reduce import itertools itertools n = int(stdin.readline().rstrip()) n int(stdin.readline().rstrip()) int stdin.readline().rstrip() stdin.readline().rstrip stdin.readline() stdin.readline stdin readline rstrip int(x) for x in stdin.readline().rstrip().split() for x in stdin.readline().rstrip().split() x stdin.readline().rstrip().split() stdin.readline().rstrip().split stdin.readline().rstrip() stdin.readline().rstrip stdin.readline() stdin.readline stdin readline rstrip split for x in stdin.readline().rstrip().split() int(x) int x a = [int(x) for x in stdin.readline().rstrip().split()] a [int(x) for x in stdin.readline().rstrip().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(x) for x in stdin.readline().rstrip().split()] [int(x) for x in stdin.readline().rstrip().split()] a n = int(stdin.readline().rstrip()) int(stdin.readline().rstrip()) n
from sys import stdin
import sys
import math
from functools import reduce
import itertools

n = int(stdin.readline().rstrip())
a = [int(x) for x in stdin.readline().rstrip().split()]

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