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 <stdio.h>
#include <stdlib.h>
#include <iostream>
#include <math.h>
#include <algorithm>
#include <string>
#include <string.h>
#include <vector>
#include <functional>
#include <queue>
#include <unordered_set>
#include <climits>

using namespace std;
typedef long long ll;

ll Recur(ll n, ll N, bool three, bool five, bool seven){
	if(n > N)
	{
		return 0;
	}
	else{
		int count = 0;
		if(three) { count += Recur(n * 10 + 3, N, three, five, seven);}
		if(five) { count += Recur(n * 10 + 5, N, three, five, seven);}
		if(seven) {count += Recur(n * 10 + 7, N, three, five, seven);}
		return count + 1;
	}
}

ll Calc(ll N){
	ll ans = 0;
	ans += Recur(0, N, true, true, true) - 1;
	ans -= Recur(0, N, true, true, false) - 1;
	ans -= Recur(0, N, true, false, true) - 1;
	ans -= Recur(0, N, false, true, true) - 1;
	ans += Recur(0, N, true, false, false) - 1;
	ans += Recur(0, N, false, true, false) - 1;
	ans += Recur(0, N, false, false, true) - 1;
	return ans;
}

int main()
{
	ll N;
	cin >> N;
	cout << Calc(N) << endl;
	return 0;
}