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.lang.reflect.Array;
import java.net.Inet4Address;
import java.nio.ByteBuffer;
import java.util.*;
public class test {
    int max = 0;
    long t[];
    boolean visited[];
    ArrayList<Integer> queue = new ArrayList<>();

    public static void main(String args[]) throws IOException {
        test obj = new test();
        obj.start();
    }

    void start() throws IOException {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        PrintStream out = System.out;
        Scanner sc = new Scanner(System.in);
        int n=sc.nextInt();
       // int k=sc.nextInt();
        StringBuilder s=new StringBuilder(n+"");
       // out.println(s);
        int len=s.length();
        int sum= (int) Math.pow(2,len)-2;
        Byte b[]=new Byte[len];
        for(int i=0;i<len;i++) {
            if (s.charAt(i) == '4')
                s.setCharAt(i, '0');
            else
                s.setCharAt(i, '1');
        }
        for(int i=0;i<len;i++)
            sum+=(s.charAt(i)-48)*Math.pow(2,len-i-1);
        out.println(sum+1);

    }

    //<---------------------------------------------------------------------------------------------------------------->//

     // to create and initialize Integer array
    private int[] intArray(int a, Scanner sc) {
        int temp[]=new int[a];
        for(int i=0;i<a;i++) {
            temp[i]=sc.nextInt();
        }
        return temp;
    }
    // to create and initialize Long Array
    private long[] longArray(int a, Scanner sc) {
        long temp[]=new long[a];
        for(int i=0;i<a;i++) {
            temp[i]=sc.nextLong();
        }
        return temp;
    }

    // displaying Map contents key--value
    public static void printMap(Map mp) {
        Iterator it = mp.entrySet().iterator();
        while (it.hasNext()) {
            Map.Entry pair = (Map.Entry)it.next();
            System.out.println(pair.getKey() + " = " + pair.getValue());
            it.remove(); // avoids a ConcurrentModificationException
        }
    }


    // Return arrayList of minimum factor of number
    // 24= 2*2*2*3;
    private ArrayList<Integer> minFactor(int a) {
        ArrayList<Integer> obj=new ArrayList<>();
        for(int i=2;i<=a;i++)
        {
            while(a!=0&&a%i==0)
            {
                obj.add(i);
                a/=i;
            }
        }
        return obj;
    }


    // check whether the number is prime or not
    public static boolean isPrimeNumber(int i) {
        int factors = 0;
        int j = 1;

        while(j <= i)
        {
            if(i % j == 0)
            {
                factors++;
            }
            j++;
        }
        return (factors == 2);
    }

    // creating and initializing arrayList
    private void initArrayList(ArrayList<Integer>[] tempa) {
        for(int i=0;i<tempa.length;i++)
            tempa[i]=new ArrayList<>();
    }

    // return factorial contents as ArrayList
    private ArrayList<Integer> factdigit(int i)
    {
        ArrayList<Integer> temp=new ArrayList<>();
        for(int j=i;j>1;j--)
        {
            temp.add(j);
        }
        return temp;
    }
    private  void println(int a[])
    {
        for(int i=0;i<a.length;i++)
            System.out.print(a[i]+" ");
    }
}