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.io.OutputStream;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.InputMismatchException;
import java.math.BigInteger;
import java.io.InputStream;

/**
 * Built using CHelper plug-in
 * Actual solution is at the top
 * @author bkand1908
 */
public class Main {
	public static void main(String[] args) {
		InputStream inputStream = System.in;
		OutputStream outputStream = System.out;
		InputReader in = new InputReader(inputStream);
		PrintWriter out = new PrintWriter(outputStream);
		Task9C solver = new Task9C();
		solver.solve(1, in, out);
		out.close();
	}
}

class Task9C {
	public void solve(int testNumber, InputReader in, PrintWriter out) {
        int n = in.readInt();
        int count = 0;
        for (int bitMask = 1; bitMask < (1 << 11); ++bitMask) {
            long value = 0;
            for (int j = 10; j >= 0; --j)
                value = 10 * value + ((bitMask & (1 << j)) >> j);
            if (value > n) break;
            ++count;
        }
        out.println(count);
	}
}

class InputReader {

        private InputStream stream;
        private byte[] buf = new byte[1024];
        private int curChar;
        private int numChars;

        public InputReader(InputStream stream) {
                this.stream = stream;
        }

        public int read() {
                if (numChars == -1)
                        throw new InputMismatchException();
                if (curChar >= numChars) {
                        curChar = 0;
                        try {
                                numChars = stream.read(buf);
                        } catch (IOException e) {
                                throw new InputMismatchException();
                        }
                        if (numChars <= 0)
                                return -1;
                }
                return buf[curChar++];
        }

        public int readInt() {
                int c = read();
                while (isSpaceChar(c))
                        c = read();
                int sgn = 1;
                if (c == '-') {
                        sgn = -1;
                        c = read();
                }
                int res = 0;
                do {
                        if (c < '0' || c > '9')
                                throw new InputMismatchException();
                        res *= 10;
                        res += c - '0';
                        c = read();
                } while (!isSpaceChar(c));
                return res * sgn;
        }

        private boolean isSpaceChar(int c) {
                return c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1;
        }

        }

