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: Wrong Answer)

#include <bits/stdc++.h>
#define rep(i, n) for (int i = 0; i < (n); ++i)
using  namespace std;
typedef long long ll;

int main() {
  int N;
  cin >> N;
  int k = 1;
  while (N / (int)pow(10,k)) ++k;
	
  int num[4] = {3,5,7,0};
  int ans = 0;
  for (int i = 0; i < (1 << 2*k); ++i) {
    int x = 0;
    bool used[4] = {0,0,0,0};
    for (int j = 0; j < k; ++j) {
      int t = (i >> 2*j) & 0b11;
      x += num[t] * (int)pow(10, j);
      used[t] = true;
    }
    if (used[0] && used[1] && used[2] && !used[3] && x <= N) ++ans;
  }
  for (int i = 3; i < k; ++i) ans += i*(i-1)*(i-2)*(int)pow(3, i-3);
  cout << ans << endl;
  return 0;
}