using System;

public class Program

{

    public static void Main()

    {

        var str = "AspNet-Version: 4.0.30319\r\nContent-Length: 2045\r\nC";

        var contentIndex = str.IndexOf("Content-Length");

        var lastIndex = str.LastIndexOf('\n', contentIndex, 1);

        Console.Write(lastIndex);

    }

}