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 (3.4.3) (judge verdict: Accepted)

N = int(input())


def dfs(numbers, appeared):
    global count
    if int(numbers) <= N:
        if appeared[0] and appeared[1] and appeared[2]:
            count += 1

        tmp1 = appeared.copy()
        tmp1[0] = True
        dfs(numbers + "3", tmp1)
        tmp2 = appeared.copy()
        tmp2[1] = True
        dfs(numbers + "5", tmp2)
        tmp3 = appeared.copy()
        tmp3[2] = True
        dfs(numbers + "7", tmp3)


count = 0
dfs("3", [True, False, False])
dfs("5", [False, True, False])
dfs("7", [False, False, True])

print(count)