package main

import (
	"bufio"
	"fmt"
	"os"
)

func main() {
	sc := bufio.NewScanner(os.Stdin)
	sc.Buffer(make([]byte, 0, 200000+2), 200000+2)
	sc.Scan()
	S := sc.Text()

	n := 0
	for i := 0; i < len(S)-3; {
		if S[i:i+4] == "pain" {
			if n >= 2 {
				fmt.Println(n - 1)
			} else {
				fmt.Println(-1)
			}
			return
		}

		if S[i:i+3] == "pon" {
			n++
			i += 3
		} else {
			i++
		}
	}
	fmt.Println(-1)
}