package main

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

func main() {
	sc := bufio.NewScanner(os.Stdin)
	sc.Scan()
	S := sc.Text()
	var cnt int
	var w bool
	min := 100
	for i := range S {
		switch S[i] {
		case 'c':
			cnt = 1
			w = false
		case 'w':
			cnt++
			if w {
				if cnt < min {
					min = cnt
				}
				w = false
			} else {
				w = true
			}
		default:
			cnt++
		}
	}
	if min == 100 {
		fmt.Println("-1")
	} else {
		fmt.Println(min)
	}
}