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."

<image>

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.*;
import java.util.*;
import java.util.zip.ZipEntry;
import java.math.*;

public class Main {
    public static void main(String[] args) {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        Input in = new Input(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        Task solver = new Task();
        solver.solve(1, in, out);
        out.close();
    }
}

class Task {
    static final long MOD = 1000000007;
    int[] primes;

    public void solve(int testNumber, Input in, PrintWriter out) {
        char[] s = in.next().toCharArray();
        int n = s.length;
        long ans = (1L << n) - 2;
        long left = 0;
        long right = 1L << n;
        for (int i = 0; i < n; i++) {
            long mid = (left + right) >> 1;
            if (s[i] == '4') {
                right = mid;
            } else {
                left = mid;
            }
        }
        out.println(ans + right);
    }

    private boolean isQuare(int[][] m) {
        long[] dist = new long[6];
        int index = 0;
        for (int i = 0; i < 4; i++) {
            for (int j = i + 1; j < 4; j++) {
                dist[index++] = dist(m[i][0], m[i][1], m[j][0], m[j][1]);
            }
        }
        Arrays.sort(dist);
        if (dist[0] == 0 || dist[5] == 0)
            return false;
        for (int i = 0; i < 2; i++) {
            if (dist[i] != dist[i + 1])
                return false;
        }

        return dist[4] == dist[5];
    }

    private long dist(long x1, long y1, long x2, long y2) {
        return (x2 - x1) * (x2 - x1) + (y2 - y1) * (y2 - y1);
    }

    static void rotate(int[][] m, int row) {
        int x = m[row][0] - m[row][2];
        int y = m[row][1] - m[row][3];
        m[row][0] = m[row][2] - y;
        m[row][1] = m[row][3] + x;
    }

    // didn't test
    static class BIT {
        int[] MAX;
        int[] MIN;
        int[] SUM;
        int n;

        public BIT(int n) {
            MAX = new int[n + 1];
            MIN = new int[n + 1];
            SUM = new int[n + 1];
            this.n = n;
        }

        public void setSum(int pos, int val) {
            for (int i = pos; i < n; i += (i & -i)) {
                SUM[i] += val;
            }
        }

        public int getSum(int to) {
            int sum = 0;
            for (int i = to; i > 0; i -= (i & -i)) {
                sum += SUM[i];
            }
            return sum;
        }

        public int getSum(int from, int to) {
            return getSum(to) - getSum(from);
        }

        public void setMax(int pos, int val) {
            for (int i = pos; i < n; i += (i & -i)) {
                MAX[i] = Math.max(val, MAX[i]);
            }
        }

        public int getMax(int to) {
            int max = 0;
            for (int i = to; i > 0; i -= (i & -i)) {
                max = Math.max(max, MAX[i]);
            }
            return max;
        }

        public void setMin(int pos, int val) {
            for (int i = pos; i < n; i += (i & -i)) {
                MIN[i] = Math.min(val, MIN[i]);
            }
        }

        public int getMin(int to) {
            int min = 0;
            for (int i = to; i > 0; i -= (i & -i)) {
                min = Math.min(min, MIN[i]);
            }
            return min;
        }

    }

    // didn't test
    static class DisjointSet {
        int[] set;

        public DisjointSet(int n) {
            set = new int[n];
            for (int i = 0; i < n; i++) {
                set[i] = i;
            }
        }

        public int findSet(int a) {
            if (set[a] == a)
                return a;
            return findSet(set[a]);
        }

        public void unionSet(int a, int b) {
            set[findSet(a)] = findSet(b);
        }

        public boolean isSameSet(int a, int b) {
            return findSet(a) == findSet(b);
        }
    }

    static class SegmentTree {
        int[] MAX;
        int[] MIN;
        int[] SUM;
        int[] data;
        int n;

        public SegmentTree(int[] data) {
            this.n = data.length;
            this.data = data;
            MAX = new int[4 * n + 10];
            MIN = new int[4 * n + 10];
            SUM = new int[4 * n + 10];
            buildTree(1, 0, n - 1);
        }

        public int left(int root) {
            return root << 1;
        }

        public int right(int root) {
            return (root << 1) + 1;
        }

        private void buildTree(int root, int rl, int rr) {
            if (rr == rl) {
                MAX[root] = MIN[root] = SUM[root] = data[rr];
            } else {
                int rm = (rl + rr) >> 1;
                buildTree(left(root), rl, rm);
                buildTree(right(root), rm + 1, rr);
                MAX[root] = Math.max(MAX[left(root)], MAX[right(root)]);
                MIN[root] = Math.min(MIN[left(root)], MIN[right(root)]);
                SUM[root] = SUM[left(root)] + SUM[right(root)];
            }
        }

        public int getMax(int from, int to) {
            return getMax(1, 0, n - 1, from, to);
        }

        private int getMax(int root, int rl, int rr, int from, int to) {
            if (from > rr || to < rl || rl > rr) {
                return -1;
            }
            if (from == rl && to == rr) {
                return MAX[root];
            }
            int rm = (rr + rl) >> 1;
            int m1 = getMax(left(root), rl, rm, from, Math.min(to, rm));
            int m2 = getMax(right(root), rm + 1, rr, Math.max(from, rm + 1), to);
            return Math.max(m1, m2);
        }

        public int getMin(int from, int to) {
            return getMin(1, 0, n - 1, from, to);
        }

        private int getMin(int root, int rl, int rr, int from, int to) {
            if (from > rr || to < rl || rl > rr) {
                return Integer.MAX_VALUE;
            }
            if (from == rl && to == rr) {
                return MIN[root];
            }
            int rm = (rr + rl) >> 1;
            int m1 = getMin(left(root), rl, rm, from, Math.min(to, rm));
            int m2 = getMin(right(root), rm + 1, rr, Math.max(from, rm + 1), to);
            return Math.min(m1, m2);
        }

        public int getSum(int from, int to) {
            return getSum(1, 0, n - 1, from, to);
        }

        private int getSum(int root, int rl, int rr, int from, int to) {
            if (from > rr || to < rl || rl > rr) {
                return 0;
            }
            if (from == rl && to == rr) {
                return SUM[root];
            }
            int rm = (rr + rl) >> 1;
            int m1 = getSum(left(root), rl, rm, from, Math.min(to, rm));
            int m2 = getSum(right(root), rm + 1, rr, Math.max(from, rm + 1), to);
            return m1 + m2;
        }
    }

    private String lcs(String s1, String s2) {
        int n = s1.length();
        int m = s2.length();
        int[][] dp = new int[n + 1][m + 1];
        for (int i = 1; i <= n; i++) {
            for (int j = 1; j <= m; j++) {
                if (s1.charAt(i - 1) == s2.charAt(j - 1)) {
                    dp[i][j] = dp[i - 1][j - 1] + 1;
                } else {
                    dp[i][j] = Math.max(dp[i - 1][j], dp[i][j - 1]);
                }
            }
        }
        StringBuilder sb = new StringBuilder();
        int i = n;
        int j = m;
        while (i > 0 && j > 0) {
            if (s1.charAt(i - 1) == s2.charAt(j - 1)) {
                sb.append(s1.charAt(i - 1));
                i--;
                j--;
            } else {
                if (dp[i - 1][j] > dp[i][j - 1]) {
                    i--;
                } else {
                    j--;
                }
            }
        }
        return sb.reverse().toString();
    }

    private boolean isPrime(int n) {
        if (n <= 3)
            return n > 1;
        else if (n % 3 == 0 || n % 2 == 0)
            return false;
        for (long i = 5; i * i <= n; i += 6) {
            if (n % i == 0 || n % (i + 2) == 0)
                return false;
        }
        return true;
    }

    private int[] getPrimes(int n) {
        int len = n + 1;
        boolean[] isPrimes = new boolean[len];
        int[] temps = new int[len];
        int index = 0;
        Arrays.fill(isPrimes, true);
        isPrimes[0] = isPrimes[1] = false;
        for (int i = 2; i * i < len; i++) {
            if (isPrimes[i]) {
                for (int j = i * i; j < len; j += i) {
                    isPrimes[j] = false;
                }
            }
        }
        for (int i = 0; i < len; i++) {
            if (isPrimes[i])
                temps[index++] = i;
        }
        int[] primes = Arrays.copyOf(temps, index);
        return primes;
    }

    static void swap(char[] arrays, int pos1, int pos2) {
        char tmp = arrays[pos1];
        arrays[pos1] = arrays[pos2];
        arrays[pos2] = tmp;
    }

    static void swap(int[] arrays, int pos1, int pos2) {
        int tmp = arrays[pos1];
        arrays[pos1] = arrays[pos2];
        arrays[pos2] = tmp;
    }

    static long modPow(long n, long ex) {
        long res = 1;
        while (ex > 0) {
            if ((ex & 1) == 1)
                res = res * n % MOD;
            n = n * n % MOD;
            ex >>= 1;
        }
        return res;
    }

    static long ModInverse(long n) {
        return modPow(n, MOD - 2);
    }

    static long nCr(int n, int r) {
        if (r > n)
            return -1;
        // return (f[n] * ModInverse((f[r] * f[n - r]) % MOD)) % MOD;
        return 0;
    }
}

class Input {
    public BufferedReader reader;
    public StringTokenizer tokenizer;

    public Input(InputStream stream) {
        reader = new BufferedReader(new InputStreamReader(stream), 32768);
        tokenizer = null;
        tokenizer = null;
    }

    public String next() {
        while (tokenizer == null || !tokenizer.hasMoreTokens()) {
            try {
                tokenizer = new StringTokenizer(reader.readLine());
            } catch (IOException e) {
                throw new RuntimeException(e);
            }
        }
        return tokenizer.nextToken();
    }

    public int nextInt() {
        return Integer.parseInt(next());
    }

    public long nextLong() {
        return Long.parseLong(next());
    }

    public double nextDouble() {
        return Double.parseDouble(next());
    }
}
