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: Accepted)

n = int(input())

ans = 0

for i in range(3, 10):
    for j in range(3**(i)):
        s = 0
        cs = [0, 0, 0]
        for k in range(i):
            s += [3, 5, 7][(j // 3**(i - k - 1)) % 3] * 10**(i - k - 1)
            cs[(j // 3**(i - k - 1)) % 3] = 1
        if sum(cs) == 3 and s <= n:
            ans += 1

print(ans)