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
// All important imports
 
import static java.lang.System.in;

import java.io.BufferedReader;
import java.io.ByteArrayInputStream;
import java.io.DataInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.lang.reflect.Array;
import java.math.BigInteger;
import java.text.DecimalFormat;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.BitSet;
import java.util.Collections;
import java.util.Comparator;
import java.util.Date;
import java.util.GregorianCalendar;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Hashtable;
import java.util.InputMismatchException;
import java.util.LinkedList;
import java.util.List;
import java.util.Map;
import java.util.Stack;
import java.util.Queue;
import java.util.Random;
import java.util.StringTokenizer;
import java.util.TreeMap;
import java.util.Vector;

public class Main{
	public static int count(int x){
		int c=0;
		while(x!=0){
			++c;
			x/=10;
		}
		return c;
	}
	public static void solve() throws IOException, Exception{
	int n=ni();
	int x=count(n);
	int s = (int)Math.pow(2,x)-2;
	int t =n;
	int c=0;
	while(t!=0){
		int d = t%10;
		if(d==7){
			s+=(int)Math.pow(2,c);
		}
		t/=10;
		c++;
	}
	out.println(s+1);
    }
    
        // END OF SOLUTION
        // INPUT OUTPUT TEMPLATE
        static String TESTCASES;
        static PrintWriter out;
	public static void main(String[] args) throws Exception,IOException{
                out=new PrintWriter(System.out);
                InputStream myinp=System.in;
                init(myinp);
              
//               int tc=ni();
//               for(int testno=0;testno<=99;testno++)

                {
                   solve(); 
               }

               
                out.close();
                
                  }
        
	
        static InputStream is;
        static BufferedReader brr;
        static int BUFFER_SIZE = 65000;
        static DataInputStream din;
        static byte[] buffer;
        static int bufferPointer, bytesRead;
        public static void init(InputStream input) {
        is=input;
        brr=new BufferedReader(new InputStreamReader(input));
        din = new DataInputStream(in);
        buffer = new byte[BUFFER_SIZE];
        bufferPointer = bytesRead = 0;
        }
    	
	
	protected static byte[] inbuf = new byte[1024];
	static int lenbuf = 0, ptrbuf = 0;
	
        static byte read() throws Exception
        {
            if (bufferPointer == bytesRead) fillBuffer();
            return buffer[bufferPointer++];
        }
        
	protected static int readByte()
	{
		if(lenbuf == -1)throw new InputMismatchException();
		if(ptrbuf >= lenbuf){
			ptrbuf = 0;
			try { lenbuf = is.read(inbuf); } catch (IOException e) { throw new InputMismatchException(); }
			if(lenbuf <= 0)return -1;
		}
		return inbuf[ptrbuf++];
	}
        
        protected static String readline() throws IOException
        {
            return brr.readLine();
        }
                
	
	
	// extras
	protected static double nd() { return Double.parseDouble(ns()); }
	protected static char nc() { return (char)skip(); }
	protected static boolean isSpaceChar(int c) { return !(c >= 33 && c <= 126); }
	protected static int skip() { 
            int b; while((b = readByte()) != -1 && isSpaceChar(b)); return b; 
        }
        static void fillBuffer() throws Exception
        {
            bytesRead = din.read(buffer, bufferPointer = 0, BUFFER_SIZE);
            if (bytesRead == -1) buffer[0] = -1;
        }
        
	protected static String ns()
	{
		int b = skip();
		StringBuilder sb = new StringBuilder();
		while(!(isSpaceChar(b))){ // when nextLine, (isSpaceChar(b) && b != ' ')
			sb.appendCodePoint(b);
			b = readByte();
		}
		return sb.toString();
	}
	
	protected static char[] nca(int n)
	{
		char[] buf = new char[n];
		int b = skip(), p = 0;
		while(p < n && !(isSpaceChar(b))){
			buf[p++] = (char)b;
			b = readByte();
		}
		return n == p ? buf : Arrays.copyOf(buf, p);
	}
	
	
	protected static int[] nia(int n)
	{
		int[] a = new int[n];
		for(int i = 0;i < n;i++)a[i] = ni();
		return a;
	}
        
        protected static int[][] niaindex(int n)
        {
                int ea[][]=new int[n][2];
                for(int i=0;i<n;i++)
                {
                    ea[i][0]=ni();
                    ea[i][1]=i;
                }
                return ea;
        }
        
        protected static long[] nla(int n)
	{
		long[] a = new long[n];
		for(int i = 0;i < n;i++)a[i] = nl();
		return a;
	}
        
        protected static long[][] nlaindex(int n)
        {
                long ea[][]=new long[n][2];
                for(int i=0;i<n;i++)
                {
                    ea[i][0]=ni();
                    ea[i][1]=i;
                }
                return ea;
        }
        
        protected static String[] nsa(int n)
	{
		String[] a = new String[n];
		for(int i = 0;i < n;i++)a[i] = ns();
		return a;
	}
        
        protected static double[] nda(int n)
	{
		double[] a = new double[n];
		for(int i = 0;i < n;i++)a[i] = nd();
		return a;
	}
	
        static int ni2() throws Exception
        {
            int ret = 0;
            byte c = read();
            while (c <= ' ') c = read();
            boolean neg = c == '-';
            if (neg) c = read();
            do
            {
                ret = ret * 10 + c - '0';
                c = read();
            } while (c > ' ');
            if (neg) return -ret;
            return ret;
 
        }
        
        
 
    
        
	protected static int ni()
	{
		int num = 0, b;
		boolean minus = false;
		while((b = readByte()) != -1 && !((b >= '0' && b <= '9') || b == '-'));
		if(b == '-'){
			minus = true;
			b = readByte();
		}
		
		while(true){
			if(b >= '0' && b <= '9'){
				num = num * 10 + (b - '0');
			}else{
				return minus ? -num : num;
			}
			b = readByte();
		}
	}
        
	
	protected static long nl()
	{
		long num = 0;
		int b;
		boolean minus = false;
		while((b = readByte()) != -1 && !((b >= '0' && b <= '9') || b == '-'));
		if(b == '-'){
			minus = true;
			b = readByte();
		}
		
		while(true){
			if(b >= '0' && b <= '9'){
				num = num * 10 + (b - '0');
			}else{
				return minus ? -num : num;
			}
			b = readByte();
		}
	}
        
        
        // Outputs
        public static void pln(){out.println();}
        public static void ps(String s){out.print(s);}
        public static void pi(int s){out.print(s);}
        public static void pl(long s){out.print(s);}
        public static void pd(double s){out.print(s);}
        public static void psp(){out.print(" ");}
        public static void parr(int s[]){out.println(Arrays.toString(s));}
        public static void parr(String s[]){out.println(Arrays.toString(s));}
        public static void parr(long s[]){out.println(Arrays.toString(s));}        
        public static void parr2(int s[][]){for(int i=0;i<s.length;i++)out.println(Arrays.toString(s[i]));}
        public static void parr2(long s[][]){for(int i=0;i<s.length;i++)out.println(Arrays.toString(s[i]));}
        public static void parr2(String s[][]){for(int i=0;i<s.length;i++)out.println(Arrays.toString(s[i]));}
 
}
    
