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 JavaScript (node.js v5.12) (judge verdict: Wrong Answer)

function Main(input){
  input=input.split("\n");
  num = input[0];
  var a = input[1].split(" ");
  a.sort(function(a,b){
    return parseInt(a,10) - parseInt(b,10);
  });
  for(var n = 0; n < num-1; n++){
    if(a[n]===a[n+1]){
      console.log("NO");
      return;
    }
  }
  console.log("YES");
}