use std::process;

fn getline() -> String{
	let mut __ret=String::new();
	std::io::stdin().read_line(&mut __ret).ok();
	return __ret;
}

fn main(){
	let s=getline();
    let mut pain_index:i32 = -1;
    if s.len() < 4 {
        print!("{}", -1);
        process::exit(0);
    }
    for i in 0..s.len()-3 {
        if &s[i..i+4] == "pain" {
            pain_index = i as i32;
            break;
        }
    }
    if pain_index == -1 {
        print!("{}", -1);
        process::exit(0);
    }
    let mut pain_num:i32 = 0;
    for i in 0..(pain_index as usize) {
        if &s[i..i+3] == "pon" {
            pain_num = pain_num + 1;
        }
    }
    match pain_num {
        0 => print!("{}", -1),
        1 => print!("{}", -1),
        _ => print!("{}", pain_num -1),
    }
}