struct Scanner<R> { r: R, buf: Vec<u8> }

impl<R: std::io::BufRead> Scanner<R> {
    fn new(r: R) -> Scanner<R> {
        Scanner { r, buf: Vec::with_capacity(8000) }
    }

    fn next(&mut self) -> &str {
        self.buf.clear();
        loop {
            let (done, used) = {
                let available = self.r.fill_buf().unwrap();
                match available.iter().position(|b| !b.is_ascii_whitespace()) {
                    Some(i) => (true, i),
                    None => (false, available.len()),
                }
            };
            self.r.consume(used);
            if done || used == 0 { break; }
        }
        loop {
            let (done, used) = {
                let available = self.r.fill_buf().unwrap();
                match available.iter().position(|b| b.is_ascii_whitespace()) {
                    Some(i) => {
                        self.buf.extend_from_slice(&available[..i]);
                        (true, i)
                    }
                    None => {
                        self.buf.extend_from_slice(&available);
                        (false, available.len())
                    }
                }
            };
            self.r.consume(used);
            if done || used == 0 {
                unsafe {
                    return std::str::from_utf8_unchecked(&self.buf);
                }
            }
        }
    }
}

macro_rules! parse {
    ($s:expr, Chars) => ($s.chars().collect::<Vec<_>>());
    ($s:expr, Bytes) => ($s.bytes().collect::<Vec<_>>());
    ($s:expr, Usize1) => (parse!($s, usize) - 1);
    ($s:expr, $t:ty) => ($s.parse::<$t>().unwrap());
}

macro_rules! read {
    ($sc:expr, [$t:tt; $n:expr]) => (
        (0..$n).map(|_| read!($sc, $t)).collect::<Vec<_>>()
    );
    ($sc:expr, ($($t:tt),*)) => (($(read!($sc, $t)),*));
    ($sc:expr, $t:ident) => (parse!($sc.next(), $t));
    ($sc:expr, $($t:tt),*) => (($(read!($sc, $t)),*));
}

fn main() {
    use std::io::Write;
    let (stdin, stdout) = (std::io::stdin(), std::io::stdout());
    let mut sc = Scanner::new(stdin.lock());
    let mut wr = std::io::BufWriter::new(stdout.lock());
    macro_rules! scan {
        ($($t:tt)*) => (read!(sc, $($t)*));
    }
    macro_rules! println {
        ($($arg:tt)*) => (writeln!(wr, $($arg)*).ok());
    }

    let n = scan!(String);
    println!("{}", (n.len() + 1) / 2);
}