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.
//package com.a2onlinejudge.ladder.CodeforcesDiv2C;

import java.io.*;
import java.util.Arrays;
import java.util.InputMismatchException;

/**
 * Created by rahulkhairwar on 13/03/16.
 */
public final class HexadecimalsNumbers
{
	static int n;
	static InputReader in;
	static OutputWriter out;

	public static void main(String[] args)
	{
		in = new InputReader(System.in);
		out = new OutputWriter(System.out);

		solve2();

		out.flush();

		in.close();
		out.close();
	}

	static void solve()
	{
		n = in.nextInt();

		int[] count = new int[10];
		int total = 1;

		count[0] = 1;

		for (int i = 1; i < 10; i++)
		{
			total = (total * 2) + 1;
			count[i] = total;
		}

		String num;
		int length, answer;

		num = "" + n;
		length = num.length();

		if (length == 1)
		{
			out.println(2);

			return;
		}

		answer = count[length - 2];

		System.out.println("answer before adding extra : " + answer);

		int min = Integer.MIN_VALUE;

		for (int i = 1; i < 10; i++)
		{
			min = Math.max(("" + n).indexOf("" + i, 1), min);

			if (min > 0)
				break;
		}

/*		System.out.println("min : " + min + ", (len - min - 2) : " + (length - min - 2) + ", count[len - min - 2] : " +
				count[length - min - 2]);*/

		if (min > 0)
			answer += count[length - min - 1] + 1;
		else
			answer++;

//		System.out.println("min : " + min);

		out.println(answer);
	}

	static void solve2()
	{
		n = in.nextInt();

		String num, converted;

		num = "" + n;
		converted = "";

		for (int i = 0; i < num.length(); i++)
		{
			if (num.charAt(i) > '1')
			{
//				converted += '1';

				for (int j = i; j < num.length(); j++)
					converted += '1';

				break;
			}
			else
				converted += num.charAt(i);
		}

		int length, power, answer;

		length = converted.length();
		power = 1;
		answer = 0;

		for (int i = length - 1; i >= 0; i--)
		{
			answer += (power * (converted.charAt(i) - '0'));
			power *= 2;
		}

		out.println(answer);
	}

	static 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 nextInt()
		{
			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 & 15;

				c = read();
			} while (!isSpaceChar(c));

			return res * sgn;
		}

		public int[] nextIntArray(int arraySize)
		{
			int array[] = new int[arraySize];

			for (int i = 0; i < arraySize; i++)
				array[i] = nextInt();

			return array;
		}

		public long nextLong()
		{
			int c = read();

			while (isSpaceChar(c))
				c = read();

			int sign = 1;

			if (c == '-')
			{
				sign = -1;

				c = read();
			}

			long result = 0;

			do
			{
				if (c < '0' || c > '9')
					throw new InputMismatchException();

				result *= 10;
				result += c & 15;

				c = read();
			} while (!isSpaceChar(c));

			return result * sign;
		}

		public long[] nextLongArray(int arraySize)
		{
			long array[] = new long[arraySize];

			for (int i = 0; i < arraySize; i++)
				array[i] = nextLong();

			return array;
		}

		public float nextFloat() // problematic
		{
			float result, div;
			byte c;

			result = 0;
			div = 1;
			c = (byte) read();

			while (c <= ' ')
				c = (byte) read();

			boolean isNegative = (c == '-');

			if (isNegative)
				c = (byte) read();

			do
			{
				result = result * 10 + c - '0';
			} while ((c = (byte) read()) >= '0' && c <= '9');

			if (c == '.')
				while ((c = (byte) read()) >= '0' && c <= '9')
					result += (c - '0') / (div *= 10);

			if (isNegative)
				return -result;

			return result;
		}

		public double nextDouble() // not completely accurate
		{
			double ret = 0, div = 1;
			byte c = (byte) read();

			while (c <= ' ')
				c = (byte) read();

			boolean neg = (c == '-');

			if (neg)
				c = (byte) read();

			do
			{
				ret = ret * 10 + c - '0';
			} while ((c = (byte) read()) >= '0' && c <= '9');

			if (c == '.')
				while ((c = (byte) read()) >= '0' && c <= '9')
					ret += (c - '0') / (div *= 10);

			if (neg)
				return -ret;

			return ret;
		}

		public String next()
		{
			int c = read();

			while (isSpaceChar(c))
				c = read();

			StringBuilder res = new StringBuilder();

			do
			{
				res.appendCodePoint(c);

				c = read();
			} while (!isSpaceChar(c));

			return res.toString();
		}

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

		public String nextLine()
		{
			int c = read();

			StringBuilder result = new StringBuilder();

			do
			{
				result.appendCodePoint(c);

				c = read();
			} while (!isNewLine(c));

			return result.toString();
		}

		public boolean isNewLine(int c)
		{
			return c == '\n';
		}

		public void close()
		{
			try
			{
				stream.close();
			} catch (IOException e)
			{
				e.printStackTrace();
			}
		}

	}

	static class OutputWriter
	{
		private PrintWriter writer;

		public OutputWriter(OutputStream stream)
		{
			writer = new PrintWriter(new BufferedWriter(new OutputStreamWriter(
					stream)));
		}

		public OutputWriter(Writer writer)
		{
			this.writer = new PrintWriter(writer);
		}

		public void println(int x)
		{
			writer.println(x);
		}

		public void print(int x)
		{
			writer.print(x);
		}

		public void println(int array[], int size)
		{
			for (int i = 0; i < size; i++)
				println(array[i]);
		}

		public void print(int array[], int size)
		{
			for (int i = 0; i < size; i++)
				print(array[i] + " ");
		}

		public void println(long x)
		{
			writer.println(x);
		}

		public void print(long x)
		{
			writer.print(x);
		}

		public void println(long array[], int size)
		{
			for (int i = 0; i < size; i++)
				println(array[i]);
		}

		public void print(long array[], int size)
		{
			for (int i = 0; i < size; i++)
				print(array[i]);
		}

		public void println(float num)
		{
			writer.println(num);
		}

		public void print(float num)
		{
			writer.print(num);
		}

		public void println(double num)
		{
			writer.println(num);
		}

		public void print(double num)
		{
			writer.print(num);
		}

		public void println(String s)
		{
			writer.println(s);
		}

		public void print(String s)
		{
			writer.print(s);
		}

		public void println()
		{
			writer.println();
		}

		public void printSpace()
		{
			writer.print(" ");
		}

		public void flush()
		{
			writer.flush();
		}

		public void close()
		{
			writer.close();
		}

	}

	static class CMath
	{
		static long power(long number, long power)
		{
			if (number == 1 || number == 0 || power == 0)
				return 1;

			if (power == 1)
				return number;

			if (power % 2 == 0)
				return power(number * number, power / 2);
			else
				return power(number * number, power / 2) * number;
		}

		static long modPower(long number, long power, long mod)
		{
			if (number == 1 || number == 0 || power == 0)
				return 1;

			number = mod(number, mod);

			if (power == 1)
				return number;

			long square = mod(number * number, mod);

			if (power % 2 == 0)
				return modPower(square, power / 2, mod);
			else
				return mod(modPower(square, power / 2, mod) * number, mod);
		}

		static long moduloInverse(long number, long mod)
		{
			return modPower(number, mod - 2, mod);
		}

		static long mod(long number, long mod)
		{
			return number - (number / mod) * mod;
		}

	}

}
