#include <iostream>
#include <algorithm>

using namespace std;

int main() {
    string a;
    cin >> a;
    reverse(a.begin(), a.end());

    int sum = 0, t = 1;
    for (int i = 0; a[i]; i++) sum += t * (a[i] - '0'), t = t * 2;

    cout << sum;
    return 0;
}

#include <iostream>
#include <cmath>

using namespace std;
int n, a[100000], i = 0;
int main() {
    cin >> n;
    while (n > 0) {
        i++;
        a[i] = n % 2;
        n /= 2;
    }

    for (int j = i; j >= 1; j--) cout << a[j];
    return 0;
}