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 <bits/stdc++.h>
typedef long long ll; 
 
using namespace std;

int func(int d, int N) {
	int res = 0;
	vector<int> v(d, 0);
	for (int i = 0; i < pow(3, d); ++i) {
		int x = i;
		for (int j = 0; j < d; ++j) {
			v[j] = x % 3;
			x /= 3;
		}

		ll sum = 0;
		bool a = false;
		bool b = false;
		bool c = false;
		for (int j = 0; j < d; ++j) {
			sum *= 10;
			if (v[j] == 0) {
				a = true;
				sum += 3;
			}
			if (v[j] == 1) {
				b = true;
				sum += 5;
			}
			if (v[j] == 2) {
				c = true;
				sum += 7;
			}
		}
		if (a && b && c) {
			if (sum <= N) { ++res; }
		}
	}

	return res;
}

int main() {
	int N;
	cin >> N;

	int d = 0;
	int x = N;
	while (x > 0) {
		++d;
		x /= 10;
	}

	int res = 0;
	for (int i = 3; i <= d; ++i) {
		res += func(i, N);
	}

	cout << res << endl;

	return 0;
}