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 Go (1.6) (judge verdict: Wrong Answer)

package main

import "fmt"

func main() {
	var n int
	fmt.Scan(&n)
	as := make([]int, n)
	for i := range as {
		fmt.Scan(&as[i])
	}

	bs := make([]int, n)
	copy(bs, as)
	if n > 1 {
		for i := 1; i < n; i++ {
			for j := i - 1; j >= 0; j-- {
				if bs[j] > bs[j+1] {
					bs[j], bs[j+1] = bs[j+1], bs[j]
				} else {
					break
				}
			}
		}
	}
	
	var msg string
	if isDistinct(bs) {
		msg = "Yes"
	} else {
		msg = "No"
	}

	fmt.Print(msg)
}

func isDistinct(bs []int) bool {
	if len(bs) > 1 {
		for i := 0; i < len(bs) - 1; i++ {
			if bs[i] == bs[i+1] {
				return false
			}
		}
	}
	return true
}