One beautiful July morning a terrible thing happened in Mainframe: a mean virus Megabyte somehow got access to the memory of his not less mean sister Hexadecimal. He loaded there a huge amount of n different natural numbers from 1 to n to obtain total control over her energy.

But his plan failed. The reason for this was very simple: Hexadecimal didn't perceive any information, apart from numbers written in binary format. This means that if a number in a decimal representation contained characters apart from 0 and 1, it was not stored in the memory. Now Megabyte wants to know, how many numbers were loaded successfully.

Input

Input data contains the only number n (1 ≤ n ≤ 109).

Output

Output the only number — answer to the problem.

Examples

Input

10


Output

2

Note

For n = 10 the answer includes numbers 1 and 10.
import java.util.Scanner;


public class C9 {

	public void run() {
		try {
			Scanner in = new Scanner(System.in);
			String n = in.next();
			int ret = (int)Math.pow(2,n.length()) - 1;
//			String tmp = "";
//			for (int i = 0; i < n.length(); i++) {
//				if (n.charAt(i) - '0' >= 1){
//					tmp += "1";
//				}
//				else {
//					tmp += "0";
//				}
//			}
//			int val = 0;
//			int pow = 1;
//			for (int i = n.length()-1; i >= 0; i--) {
//				val += ((n.charAt(i) == '1')?pow : 0);
//				pow *= 2;
//			}
//			if (val )
			int tmp = (int)Math.pow(2, n.length()) -1;
			int val = Integer.parseInt(n);
			boolean done = false;
			while (!done) {
				String tt = "";
				for (int i = 0; i < n.length(); i++) {
					if (((1 << i) & tmp) == (1<<i)) {
						tt = "1"+tt;
					}
					else {
						tt = "0" + tt;
					}
				}
				int rr = Integer.parseInt(tt);
				if (rr <= val) done = true;
				else {
					ret --;
					tmp --;
				}
			}
			System.out.println(ret);
		} catch (Exception e) {
			// TODO: handle exception
		}
	}
	
	public static void main(String[] args) {
		new C9().run();
	}
}
