CountNumbersV2

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace CountNumbersV2
{
    class CountNumbersV2
    {
        static void Main()
        {
            List<int> numbers = Console.ReadLine().Split().Select(int.Parse).ToList();
            numbers.Sort();
            int[] counterNums = new int[numbers.Max() + 1];
            foreach(int n in numbers)
            {
                counterNums[n]++;
            }
            for (int i = 0; i < counterNums.Length; i++)
            {
                if(counterNums[i] > 0)
                {
                    Console.WriteLine("{0} -> {1}",i,counterNums[i]);
                }
            }
        }
    }
}