CountNumbers

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

namespace CountNumbers
{
    class Program
    {
        static void Main(string[] args)
        {
            var sequence = Console.ReadLine().Split(' ').Select(int.Parse).ToList();
            var dictionary = sequence.GroupBy(x => x).ToDictionary(x => x.Key, x => x.Count());

            foreach (var pair in dictionary.OrderBy(x=>x.Key))
            {
                Console.WriteLine($"{pair.Key} -> {pair.Value}");
            }

        }
    }
}