One beautiful July morning a terrible thing happened in Mainframe: a mean virus Megabyte somehow got access to the memory of his not less mean sister Hexadecimal. He loaded there a huge amount of n different natural numbers from 1 to n to obtain total control over her energy.

But his plan failed. The reason for this was very simple: Hexadecimal didn't perceive any information, apart from numbers written in binary format. This means that if a number in a decimal representation contained characters apart from 0 and 1, it was not stored in the memory. Now Megabyte wants to know, how many numbers were loaded successfully.

Input

Input data contains the only number n (1 ≤ n ≤ 109).

Output

Output the only number — answer to the problem.

Examples

Input

10


Output

2

Note

For n = 10 the answer includes numbers 1 and 10.
import java.util.*;
import java.io.*;
import java.math.BigInteger;
public class HexadecimalNumbers {
    static long mod = (long) Math.pow(10, 9) + 7;
    static Reader f = new Reader();
    static Scanner S = new Scanner(System.in);
    public static void main(String[] args)throws IOException {
        PrintWriter pw = new PrintWriter(System.out);
        int n = f.nextInt();
        int ans = 0;
        
        for(int i = 1; i < 1023; i++) {
            String x = Integer.toBinaryString(i);
            if(Integer.parseInt(x) <= n)
                ans++;
        }

        pw.println(ans);
        pw.close();
    }
        
/******************************END OF MAIN PROGRAM*******************************************/
    // Fast Scanner Alternative of Scanner 
    // Uses Implementation of BufferedReader Class
    static class Reader 
    { 
        final private int BUFFER_SIZE = 1 << 16; 
        private DataInputStream din; 
        private byte[] buffer; 
        private int bufferPointer, bytesRead; 
  
        public Reader() 
        { 
            din = new DataInputStream(System.in); 
            buffer = new byte[BUFFER_SIZE]; 
            bufferPointer = bytesRead = 0; 
        } 
  
        public Reader(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') 
                    break; 
                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(); 
        } 
    }
    
    // Print in console
    static void pn(Object o){System.out.println(o);}
    static void p(Object o){System.out.print(o);}
    static void pni(Object o){System.out.println(o);System.out.flush();}

    //GCD of two integers
    static int gcd(int a, int b) {
        if(b == 0) return a;
        else {
            return gcd(b, a % b);
        }
    }
    // Input int array
    static int[] inpint(int n)throws IOException {
        int arr[] = new int[n];
        for(int i = 0; i < n; i++) 
            arr[i] = f.nextInt();
        return arr;
    }

    //Input long array
    static long[] inplong(int n)throws IOException {
        long arr[] = new long[n];
        for(int i = 0; i < n; i++) 
            arr[i] = f.nextLong();
        return arr;
    }

    // GCD of a array of integers
    static int gcdarray(int a[]) {
        int res = a[0];
        for(int i = 1; i < a.length; i++) {
            res = gcd(a[i] , res);
        }
        return res;
    }
    
    // Return boolean sieve of first n prime nos.
    static boolean[] sieve(int n) {
        boolean isprime[] = new boolean[n + 1];
        for(int i = 0; i <= n;++i) {
            isprime[i] = true;
        }
        isprime[0] = false;
        isprime[1] = false;
        for(int i = 2; i * i <= n; ++i) {
             if(isprime[i] == true) {               
                 for(int j = i * i; j <= n;j += i)
                     isprime[j] = false;
            }
        }
        return isprime;
    }

    // Return HashSet of factors of a number
    static HashSet<Long> factors(long n) {
        HashSet<Long> hs = new HashSet<Long>();
        for(long i = 1; i <= (long)Math.sqrt(n); i++) {
            if(n % i == 0) {
                hs.add(i);
                hs.add(n / i);
            }
        }
        return hs;
    }

    //Is n prime ?
    static boolean isPrime(int n) {
        if(n == 1) return false;
        int i = 2;
        while((i * i) <= n) {
            if(n % i == 0) return false;
            i += 1;
        }
        return true;
    }

    // Gives next (Lexicographical) permutation of String
    public static String nextPerm(String s) {
        StringBuffer sb = new StringBuffer(s);
        String ans = "No Successor";
        int ii = -1 , jj = -1;
        for(int i = 0; i < s.length() - 1; i++) {
            if((int)s.charAt(i) < (int)s.charAt(i + 1))
                ii = i;
        }
        for(int j = ii + 1; j < s.length() && j != 0; j++) {
            if((int)s.charAt(j) > (int)s.charAt(ii))
                jj = j;
        }
        if(ii == -1)
            return ans;
        else {
        char tempi = s.charAt(ii);
        char tempj = s.charAt(jj);
        sb.setCharAt(jj , tempi);
        sb.setCharAt(ii , tempj);
        StringBuffer sub = new StringBuffer(sb.substring(ii + 1));
        sub.reverse();
        int v = sub.length();
        while(v-- > 0) {
            sb.deleteCharAt(sb.length() - 1);
        }
        sb.append(sub);
        ans = sb.toString();
        return ans;
        }
    }
}