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# (Mono 4.6.2.0) (judge verdict: Time Limit Exceeded)

using System;

class DistinctOrNot
{
    static void Main(string[] args)
    {
        var times = int.Parse(Console.ReadLine());
        var input = Console.ReadLine().Split(' ');
        var output = "";
        for(var i = 0; i< times; i++)
        {
            for(var j = i + 1; j < times; j++)
            {
                if(input[i] == input[j])
                {
                    output = "NO";
                    goto loop;
                }
            }
        }
        output = "YES";
        loop:
        Console.WriteLine(output);
    }
}