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 C# (.NET Core 3.1.201) (judge verdict: Accepted)

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.ComponentModel.DataAnnotations;
using System.Linq;
using System.Runtime.InteropServices.ComTypes;
using System.Text;
using System.Threading;

class Program
{
  
    
    static void Main(string[] args)
    {
        Console.ReadLine();
        int[] arr = Console.ReadLine().Split(' ').Select(v => int.Parse(v)).ToArray();
        var a = arr.GroupBy(v => v);
        foreach(var ele in a)
        {
            if(ele.Count() != 1)
            {
                Console.WriteLine("NO");
                return;
            }
        }
        Console.WriteLine("YES");


    }




}