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>
#include <iomanip>
#include <cstdio>
#include <math.h>
#include <vector>
#include <map>
#include <queue>
#include <utility>
#include <algorithm>
#include <string>
#include <set>
#include <random>
using namespace std;
int main() {
  int N;
  cin >> N;
  int ans = 0;
  for (int i = 0; i < 262144; i++) {
	  int tmp   = i;
	  int num   = 0;
	  bool flag = true;
	  bool c[4] = { };
	  while (tmp > 0) {
		  if (tmp % 4 == 0) {
			  flag = false;
			  break;
			}
		  c[tmp % 4] = true;
		  num        = 10 * num + 2 * (tmp % 4) + 1;
		  tmp       /= 4;
		}
	  if (flag && c[1] && c[2] && c[3] && num <= N) {
		  ans++;
		}
	}
  cout << ans << endl;
  return 0;
}