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>
#include <type_traits>
using namespace std;

using ll = int64_t;
#define int ll

#define FOR(i, a, b) for (int i = int(a); i < int(b); i++)
#define REP(i, b) FOR(i, 0, b)
#define MP make_pair
#define PB push_back
#define EB emplace_back
#define ALL(x) x.begin(), x.end()

using pi = pair<int, int>;
using vi = vector<int>;
using ld = long double;

template <class T, class U>
ostream &operator<<(ostream &os, const pair<T, U> &p) {
  os << "(" << p.first << "," << p.second << ")";
  return os;
}

template <class T>
ostream &operator<<(ostream &os, const vector<T> &v) {
  os << "{";
  REP(i, (int)v.size()) {
    if (i) os << ",";
    os << v[i];
  }
  os << "}";
  return os;
}

ll read() {
  ll i;
  scanf("%" SCNd64, &i);
  return i;
}

void printSpace() { printf(" "); }

void printEoln() { printf("\n"); }

void print(ll x, int suc = 1) {
  printf("%" PRId64, x);
  if (suc == 1) printEoln();
  if (suc == 2) printSpace();
}

string readString() {
  static char buf[3341000];
  scanf("%s", buf);
  return string(buf);
}

char *readCharArray() {
  static char buf[3341000];
  static int bufUsed = 0;
  char *ret = buf + bufUsed;
  scanf("%s", ret);
  bufUsed += strlen(ret) + 1;
  return ret;
}

template <class T, class U>
void chmax(T &a, U b) {
  if (a < b) a = b;
}

template <class T, class U>
void chmin(T &a, U b) {
  if (b < a) a = b;
}

template <class T>
T Sq(const T &t) {
  return t * t;
}

const int mod = 1e9 + 7;

int ans = 0;
int n, digitCount;
int kind[] = {0, 3, 5, 7};

void is753(int array[]) {
  int target = 0;
  REP(i, digitCount) { target += array[i] * pow(10, i); }
  if (target > n) return;
  int remain;
  bool is3, is5, is7;
  is3 = is5 = is7 = false;
  while (target != 0) {
    remain = target % 10;
    if (remain == 7) {
      is7 = true;
    } else if (remain == 5) {
      is5 = true;
    } else if (remain == 3) {
      is3 = true;
    } else {
      return;
    }
    target /= 10;
  }
  if (is7 == true && is5 == true && is3 == true) ans++;
}

void dfs(int array[], int index) {
  if (index >= digitCount) {
    is753(array);
    return;
  }
  for (int i = 0; i < 4; i++) {
    array[index] = kind[i];
    dfs(array, index + 1);
  }
}

signed main() {
  n = read();
  digitCount = 0;
  int tmp = n;
  while (tmp != 0) {
    tmp /= 10;
    digitCount++;
  }
  int array[digitCount];
  dfs(array, 0);
  print(ans);
}