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.chomp.to_i
ans = 0

ary357 = ['3','5','7']

# 3...9桁を考える上で、iとaryに対して、
# aryがi個入った配列を返してくれるメソッドが欲しくなりました
def retarys(int, ary)
  retary = []
  int.times {retary << ary}
  retary
end

# ３桁と同じことを繰り返すだけです。*で配列を展開して渡せることを利用して、
# retarysという自家製メソッドでi個ary357を渡してます。
2.step(8){|i|
  # ary357.product(*retarys(i,ary357))　でi+1桁の3,5,7からなる整数を全列挙してます
  # count は trueの数を返してくれる便利な子です。
  ans += ary357.product(*retarys(i,ary357)).count {
    |aa| (aa.uniq.size == 3) && (aa.inject(:+).to_i <= n)
  }
}
puts ans