using System;
public class Program
{
static int CountTheWord(string str)
if(str == null)
return 0;
int count = 0;
string word = "C#";
str = str.ToLower();
foreach (var ch in str)
if(word.IndexOf (ch) != -1)
count++;
}
return count;
public static void Main()
Console.WriteLine("Enter a sentence wich contains C#:");
Console.ReadLine();
