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)

import sys


def input():
    return sys.stdin.readline().strip()


sys.setrecursionlimit(20000000)

MOD = 10 ** 9 + 7
INF = float("inf")


def main():
    N = int(input())

    def f(s):
        if int(s) > N:
            return 0
        p = 0
        if len(set(list(s))) == 3:
            p = 1
        return f(s + "3") + f(s + "5") + f(s + "7") + p

    answer = f("3") + f("5") + f("7")
    print(answer)


if __name__ == "__main__":
    main()