#include<bits/stdc++.h>
using namespace std;
const int Maxn = 1e6 + 5;
double f[Maxn];
void solve()
{
    string s;
    cin >> s;
    int n = s.length();
    double ans = 0;
    int cnt = 0;
    f[0] = 0;
    f[1] = 1;
    for(int i = 2; i <= n; i++)
    {
        f[i] = max(sqrt(i), f[i - 2] + 1.0);
    }
    for(int i = 0; i < n; i++)
    {
        if(s[i] == '1')
        {
            cnt++;
        }
        if(s[i] == '0' || i == n - 1)
        {
            ans += f[cnt];
            cnt = 0;
        }
    }
    printf("%.15lf\n", ans);
}
int main()
{
    //cin.tie(0)->sync_with_stdio(false);
    solve();
    return 0;
}