using NUnit.Framework;

using System;

​

public class Program

{

    public static void Main()

    {

      Assert.AreEqual(0, getLettersCount("Hello World", 'z'));

      Assert.AreEqual(3, getLettersCount("Hello World", 'l'));

      Assert.AreEqual(1, getLettersCount("Hello World", 'd'));

      Assert.AreEqual(0, getLettersCount("", 'z'));

      Console.WriteLine("Finished");

    }

​

}