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)

# Your code here!
require 'set'

$N=gets.to_i
$ans=0

def ck(num)
    st=Set.new
    while(num>0)
        n=num%10
        st.add(n)
        num/=10
    end
    #puts st.size
    if(st.size>=3)
        return true
    else
        return false
    end
end

def calc(num,f)
    if(num>$N)
        return
    end
    if(!f&&ck(num))
        f=true
    end
    if(f==true)
        $ans=$ans+1
    end
    num*=10
    calc(num+3,f)
    calc(num+5,f)
    calc(num+7,f)
end

calc(0,false)
puts $ans