#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef unsigned long long ull;


ll n, ans;

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