module Main where

import Data.List (isInfixOf)

type Input  = String
type Output = Int

parse :: String -> Input
parse = head . lines

solve :: Input -> Output
solve input =
    let
        cond1 = isInfixOf "pain" input

        f ('p':'a':'i':'n' : s) = ""
        f (c : s)               = c : f s
        f _                     = ""

        g ('p':'o':'n' : s) = 1 + g s
        g (c : s)           = g s
        g _                 = 0

        cnt = g . f $ input

        cond2 = cnt >= 2
    in
        if cond1 && cond2 then
            cnt - 1
        else
            -1

render :: Output -> String
render = show

main :: IO ()
main =
    interact
        ( render
        . solve
        . parse
        )