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)

s = readline.chomp.to_i

def is_753(x)
  found = {}
  x.to_s.each_char do |c|
    case c
    when '3','5','7'
      found[c] = true
    else
      return false
    end
  end
  found['3'] and found['5'] and found['7']
end

def dfs(n, upper, ans)
  if n > upper
    return
  end
  if is_753(n)
    ans << n
  end
  dfs( n*10 + 3, upper, ans )
  dfs( n*10 + 5, upper, ans )
  dfs( n*10 + 7, upper, ans )
end

ans = []
dfs(0, s, ans)
puts ans.size