Once again Tavas started eating coffee mix without water! Keione told him that it smells awful, but he didn't stop doing that. That's why Keione told his smart friend, SaDDas to punish him! SaDDas took Tavas' headphones and told him: "If you solve the following problem, I'll return it to you."

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The problem is: 

You are given a lucky number n. Lucky numbers are the positive integers whose decimal representations contain only the lucky digits 4 and 7. For example, numbers 47, 744, 4 are lucky and 5, 17, 467 are not.

If we sort all lucky numbers in increasing order, what's the 1-based index of n? 

Tavas is not as smart as SaDDas, so he asked you to do him a favor and solve this problem so he can have his headphones back.

Input

The first and only line of input contains a lucky number n (1 ≤ n ≤ 109).

Output

Print the index of n among all lucky numbers.

Examples

Input

4


Output

1


Input

7


Output

2


Input

77


Output

6
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintStream;
import java.io.BufferedOutputStream;
import java.io.PrintWriter;
import java.util.InputMismatchException;

public class Main {

	public static void main(String[] args) {
		if (args.length > 0 && args[0].toLowerCase().equals("local")) {
			try {
				System.setIn(new FileInputStream("input.txt"));
				System.setOut(new PrintStream(new File("output.txt")));
			} catch (IOException exc) {
			}
		}
		Task task = new Task();
		task.solve();
	}

	public static class Task {
		static final long MOD = (long) 1e9 + 7;
		static final PrintWriter out = new PrintWriter(new BufferedOutputStream(System.out));

		public void solve() {
			try {
				Scan sc = new Scan();
				char[] ip = sc.scanString().toCharArray();
				int len = ip.length;
				int pos = 0;
				for (int i = 0; i < len; ++i) {
					if (i == 0) {
						pos = (ip[0] == '4' ? 1 : 2);
						continue;
					} else {
						pos = (pos - 1) * 2 + (ip[i] == '4' ? 1 : 2);
					}

				}

				pos += (len > 1 ? -2 + (1 << (len)) : 0);
				out.println(pos);

			} finally {
				out.close();
			}
		}

		private void debug(Object... x) {
			StringBuilder sb = new StringBuilder();
			for (Object o : x)
				sb.append(String.valueOf(o)).append(" ");
			out.println(sb);
		}
	}

	public static class Scan {
		private byte[] buf = new byte[1024];
		private int index;
		private InputStream in;
		private int total;

		public Scan() {
			in = System.in;
		}

		public int scan() {
			if (total < 0)
				throw new InputMismatchException();
			if (index >= total) {
				index = 0;
				try {
					total = in.read(buf);
				} catch (IOException e) {
					throw new RuntimeException(e);
				}
				if (total <= 0)
					return -1;
			}
			return buf[index++];
		}

		public long scanLong() {
			long integer = 0;
			int n = scan();
			while (isWhiteSpace(n))
				n = scan();
			int neg = 1;
			if (n == '-') {
				neg = -1;
				n = scan();
			}
			while (!isWhiteSpace(n)) {
				if (n >= '0' && n <= '9') {
					integer *= 10;
					integer += n - '0';
					n = scan();
				} else
					throw new InputMismatchException();
			}
			return neg * integer;
		}

		public double scanDouble() {
			double doub = 0;
			int n = scan();
			while (isWhiteSpace(n))
				n = scan();
			int neg = 1;
			if (n == '-') {
				neg = -1;
				n = scan();
			}
			while (!isWhiteSpace(n) && n != '.') {
				if (n >= '0' && n <= '9') {
					doub *= 10;
					doub += n - '0';
					n = scan();
				} else
					throw new InputMismatchException();
			}
			if (n == '.') {
				n = scan();
				double temp = 1;
				while (!isWhiteSpace(n)) {
					if (n >= '0' && n <= '9') {
						temp /= 10;
						doub += (n - '0') * temp;
						n = scan();
					} else
						throw new InputMismatchException();
				}
			}
			return doub * neg;
		}

		public String scanString() {
			StringBuilder sb = new StringBuilder();
			int n = scan();
			while (isWhiteSpace(n))
				n = scan();
			while (!isWhiteSpace(n)) {
				sb.append((char) n);
				n = scan();
			}
			return sb.toString();
		}

		public char scanChar() {
			int n = scan();
			while (isWhiteSpace(n))
				n = scan();
			return (char) n;
		}

		private boolean isWhiteSpace(int n) {
			if (n == ' ' || n == '\n' || n == '\r' || n == '\t' || n == -1)
				return true;
			return false;
		}
	}
}