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 Python (3.8.2) (judge verdict: Accepted)

from collections import deque
N = int(input())

ans = 0
ls = ['3','5','7']
for x in ls:
    st = deque([])
    flag = False
    st.append((x, flag))
    while st:
        cur, f = st.pop()
        if f:
            ans += 1
        else:
            if '3' in set(list(cur)) and '5' in set(list(cur)) and '7' in set(list(cur)):
                # print(cur)
                f = True
                ans += 1
        for y in ls:
            if int(cur + y) <= N:
                st.append((cur+y, f))
print(ans)