public static void Main()
string text = "We are living in a yellow submarine. We don't have anything else." +
"Inside the submarine is very tight." +
"So we are drinking all the day." +
"We will move out of it in 5 days.";
int index = text.IndexOf(keyLetter);
Console.WriteLine("Letter \"{0}\" found at index {1}", keyLetter, index);
index = text.IndexOf(keyLetter, index + 1);