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


int main() {
    const int n = 1e6 + 5;
    vector <double> f(n);
    f[1] = 1;
    for (int i = 2; i < n; i++) {
        f[i] = sqrt(i);
        int cnt = 0;
        for (int j = 1; j < i; j++) {
            f[i] = max(f[i], f[j] + f[i - j - 1]);
            if (++cnt > 10) break;
        }
    }

    string s;
    cin >> s;
    double ans = 0;
    for (int i = 0; i < s.size(); i++) {
        if (s[i] == '0') continue;
        int j = i;
        while (j < s.size() && s[j] == '1') j++;
        ans += f[j - i];
        i = j - 1;
    }
    cout << fixed << setprecision(10) << ans << '\n';
}