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 Kotlin (1.0.0) (judge verdict: Time Limit Exceeded)

fun main (args : Array<String>) {
    val n = readLine()!!.toInt()
    val list = readLine()!!.split(" ")

    var aList : MutableList<Int> = mutableListOf()
    var flag : Boolean = false

    for (i in list) {
        aList.add(i.toInt())
    }

    aList.sort()

    for (i in 0..n - 1) {
        if (flag) {
            break
        }
        for (j in (i + 1)..n - 1) {
            if (aList[i] != aList[j]) {
                continue
            } else {
                flag = true
                break
            }
        }
    }

    if (flag) {
        println("NO")
    } else {
        println("YES")
    }

}