use std::io::*;
use std::str::FromStr;

fn main() {
    exec(read());
}

fn exec(a: String) {
    println!("{}", answer_count(a.chars().collect()));
}

fn answer_count(mut r: Vec<char>) -> i64 {
    let first_cww_char = 'c';
    for (i, v) in r.iter().enumerate() {
        if v == &first_cww_char {
            let c_head_arr: Vec<char> = r.drain(i..).collect();
            return count_cww(c_head_arr);
        }
    }
    -1
}

fn count_cww(mut r: Vec<char>) -> i64 {
    let mut acc: Vec<char> = vec![];
    let c = r.remove(0);
    acc.push(c);
    let count = 1;
    rec_cww(r, acc, count)
}

fn rec_cww(mut r: Vec<char>, mut acc: Vec<char>, c: i64) -> i64 {
    if &acc.len() == &3 {
        return c;
    }
    if r.is_empty() {
        return -1;
    }
    let head = r.remove(0);
    let c = c + 1;
    if head == 'w' {
        acc.push(head);
    }
    rec_cww(r, acc, c)
}

fn read<T: FromStr>() -> T {
    let stdin = stdin();
    let stdin = stdin.lock();
    let token: String = stdin
        .bytes()
        .map(|c| c.expect("failed to read char") as char)
        .skip_while(|c| c.is_whitespace())
        .take_while(|c| !c.is_whitespace())
        .collect();
    token.parse().ok().expect("failed to parse token")
}