using System;

using System.Linq;

using System.Collections.Generic;

public class Program

{

    public static void Main()

    {

        Console.WriteLine(UniqueDigits("112333344555"));

        Console.WriteLine();

        foreach (var item in UniqueDigitsEntries("112333344555"))

            Console.WriteLine($"Digit: {item.Item1} occures {item.Item2} times");

    }

    private static int UniqueDigits(string str) => str.Where(x => char.IsDigit(x)).Distinct().Count();

    private static IEnumerable<(char, int)> UniqueDigitsEntries(string str) => str.Where(x => char.IsDigit(x)).GroupBy(x => x).Select(x => (x.Key, x.Count()));

}