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)

function Main(input) {
	var input = input.split("\n");
	var n = input[0];
	var a = input[1].split(" ");
	var i,j;
	var flg = true;

	for(i = 0; i < n; i++) {
		for(j = (i + 1); j < n; j++) {
			if(a[i] === a[j]) {
				flg = false;
				break;
			}
		}
	}

	console.log((flg)? "YES" : "NO");
}
Main(require("fs").readFileSync("/dev/stdin", "utf8"));