use std::io::*;

fn main() {
    let mut s: String = String::new();
    std::io::stdin().read_to_string(&mut s).ok();
    let mut itr = s.trim().split_whitespace();
    let s = format!("{}{}", itr.next().unwrap(), itr.next().unwrap());
    let s = s.split('x');

    let mut ans = 0;
    for w in s {
        ans = std::cmp::max(ans, w.len());
    }
    println!("{}", ans);
}