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: Time Limit Exceeded)

"use strict"
function Main(input) {
  input = input.trim().split('\n');
  const N = Number(input[0].trim());
  const A = input[1].trim().split(' ').map(Number);
  
  let ret = 'YES';
  for(let i=0; i<N; i++){
    let r = A.filter((val) => {
      return val === A[i];
    })
    if(r.length > 1){
      ret = 'NO';
      break;
    }
  }

  console.log(ret);
}
Main(require("fs").readFileSync("/dev/stdin", "utf8"));