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 Ruby (2.3.3) (judge verdict: Accepted)

n = gets.to_i

cands = [3,5,7]

$nums = []
def dfs(n, cands)
  return if n && n >= 10**9
  cands.each do |c|
    nn = "#{n}#{c}".to_i
    $nums << nn
    dfs(nn, cands)
  end
end

dfs(nil, cands)

nums = []
$nums.each do |num|
  flg = true
  ["3","5","7"].each do |c|
    flg = false unless num.to_s.chars.include?(c)
  end
  if flg
    nums << num
  end
end

nums.sort!

ans = 0
nums.each do |num|
  if num > n
    break
  else
    ans += 1
  end
end

puts ans