Get system uptime using C#

string uptime = String.Empty;

uptime += (Environment.TickCount / 86400000).ToString() + " days, ";

uptime += (Environment.TickCount / 3600000 % 24) + " hours, ";

uptime += (Environment.TickCount / 120000 % 60) + " minutes, ";

uptime += (Environment.TickCount / 1000 % 60) + " seconds.";

MessageBox.Show(uptime);