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: Runtime Error)

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using Console = System.Console;

namespace Atcoder
{
    class Program
    {

        static void Main(string[] args)
        {
            var N = ReadInt();
            List<int> inputList = new List<int>();
            
            for (int i = 0; i < N; i++)
            {
                var r = ReadInt();
                if (inputList.Contains(r))
                {
                    Console.WriteLine("NO");
                    return;
                }
                inputList.Add(r);
            }
            Console.WriteLine("YES");   
        }
        private static readonly Func<string> Read = () => Console.ReadLine();
        private static readonly Func<string[]> ReadStringArray = () => Console.ReadLine().Split();
        private static readonly Func<int> ReadInt = () => int.Parse(Console.ReadLine());
        private static readonly Func<long> ReadLong = () => long.Parse(Console.ReadLine());
        private static readonly Func<int[]> ReadIntArray = () => Console.ReadLine().Split().Select(int.Parse).ToArray();
        private static readonly Func<long[]> ReadLongArray = () => Console.ReadLine().Split().Select(long.Parse).ToArray();
        private static readonly Action<string> Cw = str => Console.WriteLine(str);
    }
}