Problem:
Score : 300 points

Problem Statement

Given is a sequence of integers A_1, A_2, ..., A_N.
If its elements are pairwise distinct, print YES; otherwise, print NO.

Constraints

2 ≤ N ≤ 200000

1 ≤ A_i ≤ 10^9

All values in input are integers.

Input

Input is given from Standard Input in the following format:

N
A_1 ... A_N

Output

If the elements of the sequence are pairwise distinct, print YES; otherwise, print NO.

Sample Input 1

5
2 6 1 4 5

Sample Output 1

YES

The elements are pairwise distinct.

Sample Input 2

6
4 1 3 1 6 2

Sample Output 2

NO

The second and fourth elements are identical.

Sample Input 3

2
10000000 10000000

Sample Output 3

NO

Solution in PHP (5.6.30) (judge verdict: Wrong Answer)

<?php
  fscanf(STDIN, "%d", $n);
while ($a = fgets(STDIN)){
$s = explode(" ", $a);
 $value_count = array_count_values($s);
   $max = max($value_count); // 最大の出現回数を取得する
    if ($max == 1) {
        echo "Yes";
    } else {
        echo "No";
    }
}
?>