package main

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

func main() {
	sc := bufio.NewScanner(os.Stdin)
	sc.Scan()
	S := sc.Text()
	r := regexp.MustCompile(`c[^c]*?w.*?w`)
	matches := r.FindAllStringSubmatch(S, -1)
	if len(matches) == 0 {
		fmt.Println("-1")
		return
	}
	min := 100
	for _, v := range matches {
		if len(v[0]) < min {
			min = len(v[0])
		}
	}
	fmt.Println(min)
}