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 Go (1.14.1) (judge verdict: Accepted)

package main

import (
	"fmt"
	"strconv"
)

func main() {
	var N int
	fmt.Scan(&N)
	fmt.Println(f(N, "", true, true, true))
}

func f(N int, s string, r7, r5, r3 bool) int {
	n, _ := strconv.Atoi(s)
	if n > N {
		return 0
	}
	ret := 0
	if !r7 && !r5 && !r3 {
		ret++
	}
	ret += f(N, s+"7", false, r5, r3)
	ret += f(N, s+"5", r7, false, r3)
	ret += f(N, s+"3", r7, r5, false)
	return ret
}