/**
*************************************************
   Skra: T203Fv4_6.cs
   Hofundur: Ragnar Geir Brynjolfsson.
   Dagsetning: 29.09.2009.
*************************************************
*/
using System;
class T203Fv4_6 {
  static void Main() {
    int veldi=0;
    int summa=0;
    Console.Write("Sladu inn tviundartolu: ");
    String tala = Console.ReadLine();
    for(int i=tala.Length-1;i>=0;i--)
      //2 i haekkandi veldi sinnum 0 eda 1:
      summa+=(int)Math.Pow(2,veldi++)*Convert.ToInt32(tala.Substring(i,1));
    Console.WriteLine("Samsvarandi tugakerfistala er: " + summa);
  } 
}