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>

#ifdef _PRINTDEBUG
  #include "lib/printdebug.hpp"
#else
  #define printdebug(...) 1
#endif
#define MOD_1_000_000_007 (1000000007)
#define IINF (1<<28)
#define LINF (1LL<<60)
#define rep(i, n)      REP(i, 0, (n))
#define repc(i, n)     REPC(i, 0, (n))
#define REP(i, n, m)   for (int i = (int)(n); i <  (int)(m); i++)
#define REPC(i, n, m)  for (int i = (int)(n); i <= (int)(m); i++)
#define REPCM(i, n, m) for (int i = (int)(n); i >= (int)(m); i--)
#define yesno(cond)       YESNO((cond), "Yes", "No")
#define YESNO(cond, a, b) cout << ((cond) ? (a) : (b)) << "\n"

namespace solver {
  using namespace std;
  typedef long long ll;

  int N, ans;

  void init() {
    cin >> N;
  }

  void rec(int n, int d, int three, int five, int seven, int last) {
    if(d > 8 || last == 0) {
      if (three && five && seven && 1 <= n && n <= N) {
        ans++;
      }
      return;
    }
    rec(n + 0 * pow(10, d), d+1, three+0, five+0, seven+0, 0);
    rec(n + 3 * pow(10, d), d+1, three+1, five+0, seven+0, 3);
    rec(n + 5 * pow(10, d), d+1, three+0, five+1, seven+0, 5);
    rec(n + 7 * pow(10, d), d+1, three+0, five+0, seven+1, 7);
  }

  void solve() {
    rec(0, 0, 0, 0, 0, -1);
    cout << ans << "\n";
  }
}

int main() {
  std::ios::sync_with_stdio(false);
  std::cin.tie(0);
  solver::init();
  solver::solve();
  return 0;
}