use std::cmp::{max, min};

fn main() {
    input! {
        s: bytes
    }

    let mut c0 = 0;
    let mut c1 = 0;

    for &i in &s {
        if i == b'1' {
            c1 += 1;
        } else {
            c0 += 1;
        }
    }

    let mut ans = 0.0;
    // sq(x) = sq(x / 2)               odd
    //       = sq(x / 2) + sq(x / 2 - 1) even

    struct ENV {
        cache: Vec<f64>,
    }
    let mut env = ENV {
        cache: vec![-1.0; 1_000_010],
    };

    fn calc(x: i64, env: &mut ENV) -> f64 {
        if x <= 0 {
            return 0.0;
        }
        if x == 1 {
            return 1.0;
        }
        if env.cache[at(x)] != -1.0 {
            return env.cache[at(x)];
        }

        let mut res = f64::sqrt(x as f64);
        if x % 2 == 0 {
            let cur = calc(x / 2, env) + calc((x / 2) - 1, env);
            if cur > res {
                res = cur;
            }
        } else {
            let cur = 2.0 * calc(x / 2, env);
            if cur > res {
                res = cur;
            }
        }
        env.cache[at(x)] = res;
        res
    }

    let n = s.len();
    let mut i = 0;
    while i < n {
        if s[i] == b'0' {
            i += 1;
            continue;
        }

        let st = i;
        while i < n && s[i] == b'1' {
            i += 1;
        }
        let len = i - st;
        ans += calc(len as i64, &mut env);
    }

    println!("{}", ans);
}

fn at(i: i64) -> usize {
    i as usize
}

#[macro_export]
macro_rules! input {
    () => {};
    (mut $var:ident: $t:tt, $($rest:tt)*) => {
        let mut $var = __input_inner!($t);
        input!($($rest)*)
    };
    ($var:ident: $t:tt, $($rest:tt)*) => {
        let $var = __input_inner!($t);
        input!($($rest)*)
    };
    (mut $var:ident: $t:tt) => {
        let mut $var = __input_inner!($t);
    };
    ($var:ident: $t:tt) => {
        let $var = __input_inner!($t);
    };
}

#[macro_export]
macro_rules! __input_inner {
    (($($t:tt),*)) => {
        ($(__input_inner!($t)),*)
    };
    ([$t:tt; $n:expr]) => {
        (0..$n).map(|_| __input_inner!($t)).collect::<Vec<_>>()
    };
    ([$t:tt]) => {{
        let n = __input_inner!(usize);
        (0..n).map(|_| __input_inner!($t)).collect::<Vec<_>>()
    }};
    (chars) => {
        __input_inner!(String).chars().collect::<Vec<_>>()
    };
    (bytes) => {
        __input_inner!(String).into_bytes()
    };
    (usize1) => {
        __input_inner!(usize) - 1
    };
    ($t:ty) => {
        $crate::read::<$t>()
    };
}

#[macro_export]
macro_rules! println {
    ($($arg:tt)*) => {
        $crate::write(|w| {
            use std::io::Write;
            std::writeln!(w, $($arg)*).unwrap()
        })
    };
}

#[macro_export]
macro_rules! print {
    ($($arg:tt)*) => {
        $crate::write(|w| {
            use std::io::Write;
            std::write!(w, $($arg)*).unwrap()
        })
    };
}

#[macro_export]
macro_rules! flush {
    () => {
        $crate::write(|w| {
            use std::io::Write;
            w.flush().unwrap()
        })
    };
}

pub fn read<T>() -> T
where
    T: std::str::FromStr,
    T::Err: std::fmt::Debug,
{
    use std::cell::RefCell;
    use std::io::*;

    thread_local! {
        static STDIN: RefCell<StdinLock<'static>> = RefCell::new(stdin().lock());
    }

    STDIN.with_borrow_mut(|r| {
        let mut s = vec![];
        loop {
            let buf = r.fill_buf().unwrap();
            if buf.is_empty() {
                break;
            }
            if let Some(i) = buf.iter().position(u8::is_ascii_whitespace) {
                s.extend_from_slice(&buf[..i]);
                r.consume(i + 1);
                if !s.is_empty() {
                    break;
                }
            } else {
                s.extend_from_slice(buf);
                let n = buf.len();
                r.consume(n);
            }
        }
        std::str::from_utf8(&s).unwrap().parse().unwrap()
    })
}

pub fn write<F>(f: F)
where
    F: FnOnce(&mut std::io::BufWriter<std::io::StdoutLock>),
{
    use std::cell::RefCell;
    use std::io::*;

    thread_local! {
        static STDOUT: RefCell<BufWriter<StdoutLock<'static>>> =
            RefCell::new(BufWriter::new(stdout().lock()));
    }

    STDOUT.with_borrow_mut(f)
}