#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using P = pair<int, int>;
ll MOD = 1e9 + 7;
int n;
int ans = 0;
void dfs(int x, int a, int b, int c) {
  if (x > n) return;
  if (a && b && c) {
    ans++;
  }
  dfs(10 * x + 3, 1, b, c);
  dfs(10 * x + 5, a, 1, c);
  dfs(10 * x + 7, a, b, 1);
}
int main() {
  cin >> n;
  dfs(0, 0, 0, 0);
  cout << ans << endl;
  ;
  return 0;
}
