#include <bits/stdc++.h>
using namespace std;
int n, ans = 0;
void solve(int num, bool s, bool t, bool r) {
  if (num > n) return;
  if (s && t && r) {
    ans++;
  }
  solve(num * 10 + 7, true, t, r);
  solve(num * 10 + 5, s, true, r);
  solve(num * 10 + 3, s, t, true);
}
int main() {
  cin >> n;
  solve(0, false, false, false);
  cout << ans << endl;
}
