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)

from itertools import chain
n = input()
target = list([[""]])

def next753(string_list):
    x = []
    for string in string_list:
        x.append("3" + string)
        x.append("5" + string)
        x.append("7" + string)
    return x

ans = 0
for i in range(0, len(n)):
    target.append(next753(target[i]))
new = filter(lambda x: int(x) <= int(n),list(chain.from_iterable(target[3:])))
for i in list(new):
    if (("3" in i) and ("5" in i) and ("7" in i)):
        ans += 1
print(ans)