fn main() {
    let s = std::io::read_to_string(std::io::stdin()).unwrap();

    println!("{}", output(solve(s)));
}

fn solve(s: String) -> Option<usize> {
    let mut dp = [usize::MAX; 2];
    s.bytes()
        .enumerate()
        .filter_map(|(i, s)| match s {
            b'c' => {
                dp[0] = i;
                None
            }
            b'w' => {
                if dp[1] != usize::MAX {
                    let r = i - dp[1];
                    dp[1] = dp[0];
                    Some(r)
                } else {
                    dp[1] = dp[0];
                    None
                }
            }
            _ => None,
        })
        .min()
}

fn output(ans: Option<usize>) -> String {
    match ans {
        Some(ans) => (ans + 1).to_string(),
        None => String::from("-1"),
    }
}