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.DataInputStream;
import java.io.FileInputStream;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Collections;

public class TavasAndSaddas {
    private static int solve(int n) {

        ArrayList<Long> set = new ArrayList<>();
        set.add(4l);
        set.add(7l);
        int i = 0;
        while (set.get(i) < 1e9) {

            set.add(set.get(i) * 10 + 4);
            set.add(set.get(i) * 10 + 7);
            i++;

        }
        Collections.sort(set);
        return Collections.binarySearch(set, (long)n) + 1;

    }

    public static void main(String[] args)
            throws IOException {
        Scanner s = new Scanner();
        int t = 1;
//        t = s.nextInt();
        StringBuilder ans = new StringBuilder();
        int count = 0;
        while (t-- > 0) {
            int n = s.nextInt();

            ans.append(solve(n)).append("\n");
        }
        System.out.println(ans.toString());
    }

    static class Scanner {
        final private int BUFFER_SIZE = 1 << 16;
        private DataInputStream din;
        private byte[] buffer;
        private int bufferPointer, bytesRead;

        public Scanner() {
            din = new DataInputStream(System.in);
            buffer = new byte[BUFFER_SIZE];
            bufferPointer = bytesRead = 0;
        }

        public Scanner(String file_name) throws IOException {
            din = new DataInputStream(
                    new FileInputStream(file_name));
            buffer = new byte[BUFFER_SIZE];
            bufferPointer = bytesRead = 0;
        }

        public String readLine() throws IOException {
            byte[] buf = new byte[64]; // line length
            int cnt = 0, c;
            while ((c = read()) != -1) {
                if (c == '\n') {
                    if (cnt != 0) {
                        break;
                    } else {
                        continue;
                    }
                }
                buf[cnt++] = (byte) c;
            }
            return new String(buf, 0, cnt);
        }

        public int nextInt() throws IOException {
            int ret = 0;
            byte c = read();
            while (c <= ' ') {
                c = read();
            }
            boolean neg = (c == '-');
            if (neg)
                c = read();
            do {
                ret = ret * 10 + c - '0';
            } while ((c = read()) >= '0' && c <= '9');

            if (neg)
                return -ret;
            return ret;
        }

        public long nextLong() throws IOException {
            long ret = 0;
            byte c = read();
            while (c <= ' ')
                c = read();
            boolean neg = (c == '-');
            if (neg)
                c = read();
            do {
                ret = ret * 10 + c - '0';
            } while ((c = read()) >= '0' && c <= '9');
            if (neg)
                return -ret;
            return ret;
        }

        public double nextDouble() throws IOException {
            double ret = 0, div = 1;
            byte c = read();
            while (c <= ' ')
                c = read();
            boolean neg = (c == '-');
            if (neg)
                c = read();

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

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

            if (neg)
                return -ret;
            return ret;
        }

        private void fillBuffer() throws IOException {
            bytesRead = din.read(buffer, bufferPointer = 0,
                    BUFFER_SIZE);
            if (bytesRead == -1)
                buffer[0] = -1;
        }

        private byte read() throws IOException {
            if (bufferPointer == bytesRead)
                fillBuffer();
            return buffer[bufferPointer++];
        }

        public void close() throws IOException {
            if (din == null)
                return;
            din.close();
        }
    }

    public static long norm(long a, long MOD) {
        return ((a % MOD) + MOD) % MOD;
    }

    public static long msub(long a, long b, long MOD) {
        return norm(norm(a, MOD) - norm(b, MOD), MOD);

    }

    public static long madd(long a, long b, long MOD) {
        return norm(norm(a, MOD) + norm(b, MOD), MOD);

    }

    public static long mMul(long a, long b, long MOD) {
        return norm(norm(a, MOD) * norm(b, MOD), MOD);


    }

    public static long mDiv(long a, long b, long MOD) {
        return norm(norm(a, MOD) / norm(b, MOD), MOD);
    }

    public static String formattedArray(int a[]) {
        StringBuilder res = new StringBuilder("");
        for (int e : a)
            res.append(e).append(" ");
        return res.toString().trim();

    }

}
