#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
ll ans = 0, N;

void dfs(ll x, ll a, ll b, ll 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;
} 