using System;
class Lb
{
  public static void Main(string[] args)
  {
    while(true)
     {
      Console.Write ("Enter number:");
      String s=Console.ReadLine();
      double x = double.Parse(s);
      double l = Math.Log(x, 2);
      Console.WriteLine("Lb=({0})={1}",x,l);
    
  }
//Console.ReadKey();
}
}