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 C++14 (GCC 5.4.1) (judge verdict: Accepted)

#include<iostream>
using namespace std;
using ll = long long;

ll fun(ll n, ll x){
	if (x > n)return 0;
	bool i3 = false, i5 = false, i7 = false;
	for (ll i = x; i > 0; i /= 10){
		if (i % 10 == 3)i3 = true;
		if (i % 10 == 5)i5 = true;
		if (i % 10 == 7)i7 = true;
	}
	ll res = fun(n, x * 10 + 3) + fun(n, x * 10 + 5) + fun(n, x * 10 + 7);
	if (i3 && i5 && i7)res++;
	return res;
}

int main(){
	ll n, ans = 0;
	cin >> n;
	cout << fun(n,0) << endl;
}