pub mod io {
    use std::io::{BufRead, ErrorKind};

    pub fn scan<R: BufRead>(r: &mut R) -> Vec<u8> {
        let mut res = Vec::new();
        loop {
            let buf = match r.fill_buf() {
                Ok(buf) => buf,
                Err(e) if e.kind() == ErrorKind::Interrupted => continue,
                Err(e) => panic!(e), 
            };
            let (done, used, buf) = {
                match buf.iter().position(u8::is_ascii_whitespace) {
                    Some(i) => (i > 0 || res.len() > 0, i + 1, &buf[..i]),
                    None => (buf.is_empty(), buf.len(), buf),
                }
            };
            res.extend_from_slice(buf);
            r.consume(used);
            if done { return res; }
        }
    }

    #[macro_export]
    macro_rules! scan {
        ($r:expr, [$t:tt; $n:expr]) => {
            (0..$n).map(|_| scan!($r, $t)).collect::<Vec<_>>()
        };
        ($r:expr, [$t:tt]) => {
            scan!($r, [$t; scan!($r, usize)])
        };
        ($r:expr, ($($t:tt),*)) => {
            ($(scan!($r, $t)),*)
        };
        ($r:expr, Usize1) => {
            scan!($r, usize) - 1
        };
        ($r:expr, Bytes) => {
            io::scan($r)
        };
        ($r:expr, String) => {
            String::from_utf8(scan!($r, Bytes)).unwrap()
        };
        ($r:expr, $t:ty) => {
            scan!($r, String).parse::<$t>().unwrap()
        };
    }

    #[macro_export]
    macro_rules! input {
        ($r:expr, $($($v:ident)* : $t:tt),* $(,)?) => {
            $(let $($v)* = scan!($r, $t);)*
        };
    }
}

fn run<R: std::io::BufRead, W: std::io::Write>(reader: &mut R, writer: &mut W) {
    input! {
        reader,
        s: String,
    }

    if let Some(i) = s.find("pain") {
        let count = s[..i].matches("pon").count();
        if count < 2 {
            writeln!(writer, "-1").ok();
        } else {
            writeln!(writer, "{}", count - 1).ok();
        }
    } else {
        writeln!(writer, "-1").ok();
    }
}

fn main() {
    let (stdin, stdout) = (std::io::stdin(), std::io::stdout());
    let ref mut reader = std::io::BufReader::new(stdin.lock());
    let ref mut writer = std::io::BufWriter::new(stdout.lock());
    run(reader, writer);
}