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 PHP7 (7.0.15) (judge verdict: Wrong Answer)



  <?php

  fscanf(STDIN,"%d",$N);
  $a_list = explode(" ",trim(fgets(STDIN)));


  for($i=0;$i<$N;$i++){
    $exet_check = $a_list[$i];
    unset($a_list[$i]);
    if(in_array($exet_check,$a_list)){
      echo "No\n";
      break;
    }
  }

  if($i == $N){
    echo "Yes\n";
  }