package main

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

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

	n := 0
	j := strings.Index(S, "pain")
	if j > 0 {
		for i := 0; i < j; {
			k := strings.Index(S[i:j], "pon")
			if k < 0 {
				break
			}
			n++
			i += k + 3
		}
	}

	if n >= 2 {
		fmt.Println(n - 1)
	} else {
		fmt.Println(-1)
	}
}