using System;

using System.Text;  

​

public class Program

{

    public static void Main()

    {   

        var line1 = "linia co ma 35 znakow linia co ma 1";

        var line2 = "linia co ma 35 znakow linia co ma 2";

        var line3 = "linia co ma 35 znakow linia co ma 3";

        var line4 = "linia co ma 35 znakow linia co ma 4";

        var details = new StringBuilder().AppendLine(line1).AppendLine(line2).AppendLine(line3).Append(line4).ToString();

        Console.WriteLine(details);

        Console.WriteLine(details.Length);

    }

}