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

long long n,ans;

void dfs(long long x,long long a,long long b,long long c){
  if(x>n) return; 
  if(a&&b&&c) ans++;
  dfs(x*10+3,1,b,c);
  dfs(x*10+5,a,1,c);
  dfs(x*10+7,a,b,1);
}

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