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);