using System;

​

public class Program

{

    public static void Main()

    {

        var wholeString = "List of devices attached\r\n9887bc314\tdevice\r\n12n1n2nj1jn2\tdevice\r\n\r\n";

        var splits = wholeString.Split(new[]{"device"}, StringSplitOptions.RemoveEmptyEntries);

        var device1 = splits[1].Substring(splits[1].IndexOf("\n") + 1).Replace("\t", "");

        var device2 = splits[2].Substring(splits[2].IndexOf("\n") + 1).Replace("\t", "");

        Console.WriteLine(device1);

        Console.WriteLine(device2);

    }

}