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)

// inputに入力データ全体が入る
function Main(input) {
	// ans = 0
	// 1行目がinput[0], 2行目がinput[1], …に入る
	input = input.trim().split("\n");
	bef = input[1].split(' ').map((n) => (parseInt(n)))
	bef = bef.sort()
	aft = bef.sort().filter((x, i, self) => self.indexOf(x) === i)
	var ans
	if (JSON.stringify(bef) == JSON.stringify(aft)) {
		ans = 'YES'
	} else {
		ans = 'NO'
	}


	//出力
	console.log(ans)
	}
//*この行以降は編集しないでください（標準入出力から一度に読み込み、Mainを呼び出します）
Main(require("fs").readFileSync("/dev/stdin", "utf8"));
// Main(require('fs').readFileSync('./input.txt', 'utf-8'));