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
#!/usr/bin/env python
from __future__ import division, print_function
import math
import os
import sys
from fractions import *
from sys import *
from decimal import *
from io import BytesIO, IOBase
from itertools import accumulate,combinations,permutations,combinations_with_replacement,product
from collections import *
import timeit,time
# sys.setrecursionlimit(10**5)
M = 10 ** 9 + 7
from heapq import *

# print(math.factorial(5))
if sys.version_info[0] < 3:
    from __builtin__ import xrange as range
    from future_builtins import ascii, filter, hex, map, oct, zip
# sys.setrecursionlimit(10**6)

# region fastio

BUFSIZE = 8192


class FastIO(IOBase):
    newlines = 0

    def __init__(self, file):
        self._fd = file.fileno()
        self.buffer = BytesIO()
        self.writable = "x" in file.mode or "r" not in file.mode
        self.write = self.buffer.write if self.writable else None

    def read(self):
        while True:
            b = os.read(self._fd, max(os.fstat(self._fd).st_size, BUFSIZE))
            if not b:
                break
            ptr = self.buffer.tell()
            self.buffer.seek(0, 2), self.buffer.write(b), self.buffer.seek(ptr)
        self.newlines = 0
        return self.buffer.read()

    def readline(self):
        while self.newlines == 0:
            b = os.read(self._fd, max(os.fstat(self._fd).st_size, BUFSIZE))
            self.newlines = b.count(b"\n") + (not b)
            ptr = self.buffer.tell()
            self.buffer.seek(0, 2), self.buffer.write(b), self.buffer.seek(ptr)
        self.newlines -= 1
        return self.buffer.readline()

    def flush(self):
        if self.writable:
            os.write(self._fd, self.buffer.getvalue())
            self.buffer.truncate(0), self.buffer.seek(0)


class IOWrapper(IOBase):
    def __init__(self, file):
        self.buffer = FastIO(file)
        self.flush = self.buffer.flush
        self.writable = self.buffer.writable
        self.write = lambda s: self.buffer.write(s.encode("ascii"))
        self.read = lambda: self.buffer.read().decode("ascii")
        self.readline = lambda: self.buffer.readline().decode("ascii")


def print(*args, **kwargs):
    """Prints the values to a stream, or to sys.stdout by default."""
    sep, file = kwargs.pop("sep", " "), kwargs.pop("file", sys.stdout)
    at_start = True
    for x in args:
        if not at_start:
            file.write(sep)
        file.write(str(x))
        at_start = False
    file.write(kwargs.pop("end", "\n"))
    if kwargs.pop("flush", False):
        file.flush()


if sys.version_info[0] < 3:
    sys.stdin, sys.stdout = FastIO(sys.stdin), FastIO(sys.stdout)
else:
    sys.stdin, sys.stdout = IOWrapper(sys.stdin), IOWrapper(sys.stdout)

input = lambda: sys.stdin.readline().rstrip("\r\n")


def inp(): return sys.stdin.readline().rstrip("\r\n")  # for fast input


def out(var): sys.stdout.write(str(var))  # for fast output, always take string


def lis(): return list(map(int, inp().split()))


def stringlis(): return list(map(str, inp().split()))


def sep(): return map(int, inp().split())


def strsep(): return map(str, inp().split())


def fsep(): return map(float, inp().split())


def inpu(): return int(inp())


# -----------------------------------------------------------------

def regularbracket(t):
    p = 0
    for i in t:
        if i == "(":
            p += 1
        else:
            p -= 1
        if p < 0:
            return False
    else:
        if p > 0:
            return False
        else:
            return True


# -------------------------------------------------
def binarySearchcount(arr, n, key):
    left = 0
    right = n - 1
    count = 0
    while (left <= right):
        mid = int((right + left) / 2)
        # Check if middle element is
        # less than or equal to key
        if (arr[mid] <= key):
            count = mid + 1
            left = mid + 1
        # If key is smaller, ignore right half
        else:
            right = mid - 1
    return count

#--------------------------------------------------binery search
def binarySearch(arr, n, key):
    left = 0
    right = n - 1
    while (left <= right):
        mid = ((right + left) // 2)
        if arr[mid]==key:
            return mid
        if (arr[mid] <= key):
            left = mid + 1
        # If key is smaller, ignore right half
        else:
            right = mid - 1
    return -1
#-------------------------------------------------ternary search
def ternarysearch(arr,n,key):
    l,r=0,n-1
    while(l<=r):
        mid = (-l+r)//3 + l
        mid2 = mid + (-l+r)//3
        if arr[mid]==key:
            return mid
        if arr[mid2]==key:
            return mid2
        if arr[mid]>key:
            r=mid-1
        elif arr[mid2]<key:
            l=mid2+1
        else:
            l=mid+1
            r=mid2-1
    return -1
# ------------------------------reverse string(pallindrome)
def reverse1(string):
    pp = ""
    for i in string[::-1]:
        pp += i
    if pp == string:
        return True
    return False


# --------------------------------reverse list(paindrome)
def reverse2(list1):
    l = []
    for i in list1[::-1]:
        l.append(i)
    if l == list1:
        return True
    return False


def mex(list1):
    # list1 = sorted(list1)
    p = max(list1) + 1
    for i in range(len(list1)):
        if list1[i] != i:
            p = i
            break
    return p


def sumofdigits(n):
    n = str(n)
    s1 = 0
    for i in n:
        s1 += int(i)
    return s1


def perfect_square(n):
    s = math.sqrt(n)
    if s == int(s):
        return True
    return False


# -----------------------------roman
def roman_number(x):
    if x > 15999:
        return
    value = [5000, 4000, 1000, 900, 500, 400, 100, 90, 50, 40, 10, 9, 5, 4, 1]
    symbol = ["F", "MF", "M", "CM", "D", "CD", "C", "XC", "L", "XL", "X", "IX", "V", "IV", "I"]
    roman = ""
    i = 0
    while x > 0:
        div = x // value[i]
        x = x % value[i]
        while div:
            roman += symbol[i]
            div -= 1
        i += 1
    return roman


def soretd(s):
    for i in range(1, len(s)):
        if s[i - 1] > s[i]:
            return False
    return True


# print(soretd("1"))
# ---------------------------
def countRhombi(h, w):
    ct = 0
    for i in range(2, h + 1, 2):
        for j in range(2, w + 1, 2):
            ct += (h - i + 1) * (w - j + 1)
    return ct


def countrhombi2(h, w):
    return ((h * h) // 4) * ((w * w) // 4)


# ---------------------------------
def binpow(a, b):
    if b == 0:
        return 1
    else:
        res = binpow(a, b // 2)
    if b % 2 != 0:
        return res * res * a
    else:
        return res * res


# -------------------------------------------------------
def binpowmodulus(a, b, m):
    a %= m
    res = 1
    while (b > 0):
        if (b & 1):
            res = res * a % m
        a = a * a % m
        b >>= 1
    return res


# -------------------------------------------------------------
def coprime_to_n(n):
    result = n
    i = 2
    while (i * i <= n):
        if (n % i == 0):
            while (n % i == 0):
                n //= i
            result -= result // i
        i += 1
    if (n > 1):
        result -= result // n
    return result


def luckynumwithequalnumberoffourandseven(x,n,a):
    if x >= n and str(x).count("4") == str(x).count("7"):
        a.append(x)
    else:
        if x < 1e12:
            luckynumwithequalnumberoffourandseven(x * 10 + 4,n,a)
            luckynumwithequalnumberoffourandseven(x * 10 + 7,n,a)
    return a
#----------------------
def luckynum(x,l,r,a):
    if x>=l and x<=r:
        a.append(x)
    if x>r:
        a.append(x)
        return a
    if x < 1e10:
            luckynum(x * 10 + 4, l,r,a)
            luckynum(x * 10 + 7, l,r,a)
    return a

def luckynuber(x, n, a):
    p = set(str(x))
    if len(p) <= 2:
        a.append(x)
    if x < n:
        luckynuber(x + 1, n, a)
    return a


# ------------------------------------------------------interactive problems

def interact(type, x):
    if type == "r":
        inp = input()
        return inp.strip()
    else:
        print(x, flush=True)


# ------------------------------------------------------------------zero at end of factorial of a number
def findTrailingZeros(n):
    # Initialize result
    count = 0

    # Keep dividing n by
    # 5 & update Count
    while (n >= 5):
        n //= 5
        count += n

    return count


# -----------------------------------------------merge sort
# Python program for implementation of MergeSort
def mergeSort(arr):
    if len(arr) > 1:

        # Finding the mid of the array
        mid = len(arr) // 2

        # Dividing the array elements
        L = arr[:mid]

        # into 2 halves
        R = arr[mid:]

        # Sorting the first half
        mergeSort(L)

        # Sorting the second half
        mergeSort(R)

        i = j = k = 0

        # Copy data to temp arrays L[] and R[]
        while i < len(L) and j < len(R):
            if L[i] < R[j]:
                arr[k] = L[i]
                i += 1
            else:
                arr[k] = R[j]
                j += 1
            k += 1

        # Checking if any element was left
        while i < len(L):
            arr[k] = L[i]
            i += 1
            k += 1

        while j < len(R):
            arr[k] = R[j]
            j += 1
            k += 1


# -----------------------------------------------lucky number with two lucky any digits
res = set()
def solven(p, l, a, b, n):  # given number
    if p > n or l > 10:
        return
    if p > 0:
        res.add(p)
    solven(p * 10 + a, l + 1, a, b, n)
    solven(p * 10 + b, l + 1, a, b, n)


# problem
"""
n = int(input())
for a in range(0, 10):
    for b in range(0, a):
        solve(0, 0)
print(len(res))
"""

# In the array A at every step we have two
# choices for each element either we can
# ignore the element or we can include the
# element in our subset
def subsetsUtil(A, subset, index, d):
    print(*subset)
    s = sum(subset)
    d.append(s)
    for i in range(index, len(A)):
        # include the A[i] in subset.
        subset.append(A[i])

        # move onto the next element.
        subsetsUtil(A, subset, i + 1, d)

        # exclude the A[i] from subset and
        # triggers backtracking.
        subset.pop(-1)
    return d


def subsetSums(arr, l, r, d, sum=0):
    if l > r:
        d.append(sum)
        return
    subsetSums(arr, l + 1, r, d, sum + arr[l])

    # Subset excluding arr[l]
    subsetSums(arr, l + 1, r, d, sum)
    return d


def print_factors(x):
    factors = []
    for i in range(1, x + 1):
        if x % i == 0:
            factors.append(i)
    return (factors)


# -----------------------------------------------
def calc(X, d, ans, D):
    # print(X,d)
    if len(X) == 0:
        return

    i = X.index(max(X))
    ans[D[max(X)]] = d

    Y = X[:i]
    Z = X[i + 1:]

    calc(Y, d + 1, ans, D)
    calc(Z, d + 1, ans, D)


# ---------------------------------------

def factorization(n, l):
    c = n
    if prime(n) == True:
        l.append(n)
        return l
    for i in range(2, c):
        if n == 1:
            break
        while n % i == 0:
            l.append(i)
            n = n // i
    return l


# endregion------------------------------


def good(b):
    l = []
    i = 0
    while (len(b) != 0):
        if b[i] < b[len(b) - 1 - i]:
            l.append(b[i])
            b.remove(b[i])
        else:
            l.append(b[len(b) - 1 - i])
            b.remove(b[len(b) - 1 - i])
    if l == sorted(l):
        # print(l)
        return True
    return False


# arr=[]
# print(good(arr))
def generate(st, s):
    if len(s) == 0:
        return

    # If current string is not already present.
    if s not in st:
        st.add(s)

        # Traverse current string, one by one
        # remove every character and recur.
        for i in range(len(s)):
            t = list(s).copy()
            t.remove(s[i])
            t = ''.join(t)
            generate(st, t)
    return
#=--------------------------------------------longest increasing subsequence

def largestincreasingsubsequence(A):
    l = [1]*len(A)
    sub=[]
    for i in range(1,len(l)):
        for k in range(i):
            if A[k]<A[i]:
                sub.append(l[k])
        l[i]=1+max(sub,default=0)
    return max(l,default=0)

#----------------------------------
# Function to calculate
# Bitwise OR of sums of
# all subsequences
def findOR(nums, N):
    # Stores the prefix
    # sum of nums[]
    prefix_sum = 0
    # Stores the bitwise OR of
    # sum of each subsequence
    result = 0
    # Iterate through array nums[]
    for i in range(N):
        # Bits set in nums[i] are
        # also set in result
        result |= nums[i]
        # Calculate prefix_sum
        prefix_sum += nums[i]
        # Bits set in prefix_sum
        # are also set in result
        result |= prefix_sum
    # Return the result
    return result

def OR(a, n):
    ans = a[0]
    for i in range(1, n):
        ans |= a[i]
        #l.append(ans)
    return ans

def toString(List):
    return ''.join(List)
# Function to print permutations of string
# This function takes three parameters:
# 1. String
# 2. Starting index of the string
# 3. Ending index of the string.
def permute(a, l, r,p):
    if l == r:
        p.append(toString(a))
    else:
        for i in range(l, r + 1):
            a[l], a[i] = a[i], a[l]
            permute(a, l + 1, r)
            a[l], a[i] = a[i], a[l]  # backtrack
# Function to find square root of
# given number upto given precision
def squareRoot(number, precision):
    start = 0
    end, ans = number, 1
    # For computing integral part
    # of square root of number
    while (start <= end):
        mid = int((start + end) / 2)
        if (mid * mid == number):
            ans = mid
            break

        # incrementing start if integral
        # part lies on right side of the mid
        if (mid * mid < number):
            start = mid + 1
        # decrementing end if integral part
        # lies on the left side of the mid
        else:
            end = mid - 1
    # For computing the fractional part
    # of square root upto given precision
    increment = 0.1
    for i in range(0, precision):
        while (ans * ans <= number):
            ans += increment
        # loop terminates when ans * ans > number
        ans = ans - increment
        increment = increment / 10
    return ans

def countRectangles(l, w):
    # if we take gcd(l, w), this
    # will be largest possible
    # side for suare, hence minimum
    # number of square.
    squareSide = math.gcd(l, w)
    return int((l * w) / (squareSide * squareSide))

# Function that count the
# total numbersProgram between L
# and R which have all the
# digit same
def count_same_digit(L, R):
    tmp = 0
    ans = 0
    n = int(math.log10(R) + 1)
    for i in range(0, n):
        # tmp has all digits as 1
        tmp = tmp * 10 + 1
        for j in range(1, 10):

            if (L <= (tmp * j) and (tmp * j) <= R):
                #print(tmp*j)
                # Increment the required count
                ans += 1
    return ans
#----------------------------------print k closest number of a number in an array
def findCrossOver(arr, low, high, x):
    # Base cases
    if (arr[high] <= x):  # x is greater than all
        return high
    if (arr[low] > x):  # x is smaller than all
        return low
    # Find the middle point
    mid = (low + high) // 2
    if (arr[mid] <= x and arr[mid + 1] > x):
        return mid
    if (arr[mid] < x):
        return findCrossOver(arr, mid + 1, high, x)
    return findCrossOver(arr, low, mid - 1, x)
def Kclosest(arr, x, k, n,ans):
    # Find the crossover point
    l = findCrossOver(arr, 0, n - 1, x)
    r = l + 1
    count = 0
    if (arr[l] == x):
        l -= 1
    #print(l)
    while (l >= 0 and r < n and count < k):
        if (x - arr[l] < arr[r] - x):
            ans.append(arr[l])
            l -= 1
        else:
            ans.append(arr[r])
            r += 1
        count += 1
    while (count < k and l >= 0):
        ans.append(arr[l])
        l -= 1
        count += 1
    while (count < k and r < n):
        ans.append(arr[r])
        r += 1
        count += 1
    return ans
#---------------------------------------------------------------
def prime(n):
    if n <= 1:          # negative numbers, 0 or 1
        return False
    if n <= 3:          # 2 and 3
        return True
    if n % 2 == 0 or n % 3 == 0:
        return False

    for i in range(5, int(math.sqrt(n)) + 1, 2):
        if n % i == 0:
            return False
    return True

def calcSum(arr, n, k):
    # Initialize sum = 0
    l=[]
    sum=0
    # Consider first subarray of size k
    # Store the sum of elements
    for i in range(k):
        sum += arr[i]

    # Print the current sum
    l.append(sum)

    # Consider every subarray of size k
    # Remove first element and add current
    # element to the window
    for i in range(k, n):
        # Add the element which enters
        # into the window and substract
        # the element which pops out from
        # the window of the size K
        sum = (sum - arr[i - k]) + arr[i]

        # Print the sum of subarray
        l.append(sum)

    return l


def dfs(root,nodeVal,nodeConnection,visited):
    leftVal = nodeVal[root][0]
    rightVal = nodeVal[root][1]

    solution = []
    if nodeConnection[root]:
        visited.add(root)
        for i in nodeConnection[root]:
            if i not in visited:
                solution.append(dfs(i,nodeVal,nodeConnection,visited))
        # print("solution",solution)
        leftMax = 0
        rightMax = 0
        for i in solution:
            l, r = i
            leftMax += max(abs(leftVal - l[0]) + l[1], abs(leftVal - r[0]) + r[1])
            rightMax += max(abs(rightVal - l[0]) + l[1], abs(rightVal - r[0]) + r[1])
        # print(root,"return->",(leftVal,leftMax),(rightVal,rightMax))
        return ((leftVal, leftMax), (rightVal, rightMax))
    else:
        # ((left,maxVal),(right,maxVal))
        return ((leftVal, 0), (rightVal, 0))

def luckynumber(x,n,a):
    if x >0:
        a.append(x)
    if x>10**9:
        return a
    else:
        if x < 1e12:
            luckynumber(x * 10 + 4,n,a)
            luckynumber(x * 10 + 7,n,a)
def main():
    l=[]
    n=0
    p=inpu()
    luckynumber(0,n,l)
    l.sort()
    print(l.index(p)+1)
if __name__ == '__main__':
    main()
