import java.util.*;
public class Naloga28{
	public static void main(String[]args){
		Scanner sc = new Scanner(System.in);
		int bin, ost, a = 0;
		double des = 0;
		System.out.print("Vnesi binarno st: ");
		bin = sc.nextInt();
		while (bin > 0){
			ost = bin % 10;
			if (ost == 1)
				des = Math.pow(2, a) + des;
			a++;
			bin = bin / 10;
		}
		System.out.println("Desetiško: "+des);
	}
}