Problem:
Score : 300 points

Problem Statement

You are given an integer N. Among the integers between 1 and N (inclusive), how many Shichi-Go-San numbers (literally "Seven-Five-Three numbers") are there?

Here, a Shichi-Go-San number is a positive integer that satisfies the following condition:

When the number is written in base ten, each of the digits 7, 5 and 3 appears at least once, and the other digits never appear.

Constraints

1 \leq N < 10^9

N is an integer.

Input

Input is given from Standard Input in the following format:

N

Output

Print the number of the Shichi-Go-San numbers between 1 and N (inclusive).

Sample Input 1

575

Sample Output 1

4

There are four Shichi-Go-San numbers not greater than 575: 357, 375, 537 and 573.

Sample Input 2

3600

Sample Output 2

13

There are 13 Shichi-Go-San numbers not greater than 3600: the above four numbers, 735, 753, 3357, 3375, 3537, 3557, 3573, 3575 and 3577.

Sample Input 3

999999999

Sample Output 3

26484

Solution in PyPy3 (2.4.0) (judge verdict: Wrong Answer)

def function(n):
    digit=len(str(n))
    N=str(n)
    k=int(N[0])
    if digit<3:
        return 0
    else:
        if k<3:
            return function(10**(digit-1)-1)
        elif k==3:
            return function(10**(digit-1)-1)+function(n%(10**(digit-1)))-function(10**(digit-2))+subfunction(5,7,n%(10**(digit-1)))
        elif k==4:
            return function(4*(10**(digit-1))-1)
        elif k==5:
            return function(4*(10**(digit-1))-1)+function(n%(10**(digit-1)))-function(10**(digit-2))+subfunction(3,7,n%(10**(digit-1)))
        elif k==6:
            return function(6*(10**(digit-1))-1)
        elif k==7:
            return function(6*(10**(digit-1))-1)+function(n%(10**(digit-1)))-function(10**(digit-2))+subfunction(3,5,n%(10**(digit-1)))
        else:
            return function(8*(10**(digit-1))-1)

def subfunction(a,b,n):
    digit=len(str(n))
    N=str(n)
    k=int(N[0])
    if digit<2:
        return 0
    else:
        if k<a:
            return 0
        elif k==a:
            if n%(10**(digit-1))<b*(10**(digit-1)-1)//9:
                s=0
            else:
                s=1
            return subfunction(a,b,n%(10**(digit-1)))+s
        elif a<k<b:
            return subfunction(a,b,(a+1)*(10**(digit-1))-1)
        elif k==b:
            if n%(10**(digit-1))<a*(10**(digit-1)-1)//9:
                s=0
            else:
                s=1
            return subfunction(a,b,(a+1)*(10**(digit-1))-1)+subfunction(a,b,n%(10**(digit-1)))+s
        else:
            return subfunction(a,b,(b+1)*(10**(digit-1))-1)

N=int(input())
print(function(N))