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

#define int long long

signed main() {
    int kettohatvany[60] = {0};
    kettohatvany[0] = 1;
    for(int i = 1; i < 60; i++) {
        kettohatvany[i] = kettohatvany[i-1]*2;
    }
    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 << kettohatvany[cnt]-kettohatvany[i] << endl;
            return 0;
        }
    }


    cout << cnt << endl;


}