StiliyanTest

using System.Collections.Generic;
using System;
using System.Linq;

class Program
{
    static void Main(string[] args)
    {
        //input:
        //1 1 2 3 4 5 6 6 7 8
        int[] numbers = Console.ReadLine()
        .Split(' ')
        .Select(int.Parse)
        .ToArray();

        var count = new Dictionary<double, int>();

        foreach (var num in numbers)
        {
            if (count.ContainsKey(num))
            {
                count[num]++;
            }
            else
            {
                count[num] = 1;
            }

        }
        foreach (var num in count)
        {
            Console.WriteLine($"{num.Key} keys -> {num.Value} values");
        }
        //output:
        //1 keys -> 2 values
        //2 keys -> 1 values
        //3 keys -> 1 values
        //4 keys -> 1 values
        //5 keys -> 1 values
        //6 keys -> 2 values
        //7 keys -> 1 values
        //8 keys -> 1 values
        Console.ReadLine();
    }
}