code.cs

using System;

namespace ConsoleApp7
{
    class Program
    {
        static void Main(string[] args)
        {
            Console.WriteLine("My Cool App!");
            Console.WriteLine("There are some options:");
            Console.WriteLine(" 1. Counter");
            Console.WriteLine(" 2. Adder");
            Console.WriteLine(" 3. Shaper");

            var input = Console.ReadLine();

            switch (input)
            {
                case "1":
                    Console.WriteLine("You selected '1. Counter'");
                    Console.WriteLine("What type of counter do you want?");
                    Console.WriteLine(" a) ones");
                    Console.WriteLine(" b) fives");
                    Console.WriteLine(" c) tens");

                    var subInput = Console.ReadLine();

                    switch (subInput)
                    {
                        case "a":
                            {
                                Console.WriteLine("You selected 'a) ones'");
                                Console.WriteLine("Here is a quick counter!");
                                Console.WriteLine("But first, how many iterations do you want?");

                                var iterationsString = Console.ReadLine();
                                var iterations = int.Parse(iterationsString);

                                var counter = 0;
                                for (int i = 0; i < iterations; i++)
                                {
                                    counter += 1;
                                    Console.WriteLine($"Counting {counter}");
                                }
                            }
                            break;
                        case "b":
                            {
                                Console.WriteLine("You selected 'b) fives'");
                                Console.WriteLine("Here is a quick counter!");
                                Console.WriteLine("But first, how many iterations do you want?");

                                var iterationsString = Console.ReadLine();
                                var iterations = int.Parse(iterationsString);

                                var counter = 0;
                                for (int i = 0; i < iterations; i++)
                                {
                                    counter += 5;
                                    Console.WriteLine($"Counting {counter}");
                                }
                            }
                            break;
                        case "c":
                            break;
                    }

                    break;
                case "2":
                    break;
                case "3":
                    break;
            }
        }
    }
}