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

#define int long long

signed main() {
    int n;
    cin >> n;

    int nc = n;
    int cnt = 1;
    vector<int> a;
    while(nc >= 10)  {
        cnt++;
        a.push_back(nc%10);
        nc /= 10;
    }
    a.push_back(nc%10);
    reverse(a.begin(), a.end());
    nc = n;

    bool megy = 0;
    for(int i = 0; i < cnt; i++) {
        if (a[i] < 3) {
            cout << pow(2, cnt) - pow(2, cnt-i-1) << endl;
            return 0;
        }
        //cout << a[i];
    }

    cout << pow(2, cnt) << endl;


}