#include <bits/stdc++.h>
using namespace std;

int n, cnt = 0;

void dfs(long long now, int ok){
  if(now > n) return;
  
  if(ok == 0b111) cnt++;
  dfs(now * 10 + 7, ok | 0b100);
  dfs(now * 10 + 5, ok | 0b010);
  dfs(now * 10 + 3, ok | 0b001);
}

int main(){
  cin >> n;
  dfs(0, 0);
  
  cout << cnt << endl;
}