using System;

public class Program

{

    public static void Main()

    {

        var text = "Today is a good day for help. **David Diaz He went to school. **David Diaz like apple. ";

        var pos = 0;

        var num = 0;

        var search = "**David Diaz";

         while ((pos = text.IndexOf(search, pos)) > -1)

        {

            num ++;

            pos += search.Length;

        }

        Console.WriteLine(num);

    }

}