using System;
using System.Text.RegularExpressions;
public class Test
{
	public static void Main()
	{
		var input = "stacktraceabcdefghijklmnopqrstuvwxyztacktraceabcdefghijklmnopqrswxyztacktraceabcdefghijk";
		var regex = new Regex(@".{10}");
		string result = regex.Replace(input, "$&" + Environment.NewLine);
		Console.WriteLine(result);
	}
}