import java.util.ArrayList;
import java.util.List;
import java.util.Scanner;


public class Main {
    public static class Pair {
        public Integer status;
        public Integer length;

        public Pair(Integer s, Integer l) {
            this.status = s;
            this.length = l;
        }


    }

    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        String a = scanner.next();
        String[] strArray = a.split("");
        List<Pair> pairList = new ArrayList<Pair>();
        for (String s : strArray) {
            if (s.equals("c")) {
                Pair pair = new Pair(0, 1);
                pairList.add(pair);
            } else if (s.equals("w")) {
                for (Pair p : pairList) {
                    if (p.status == 2) {
                        continue;
                    }
                    p.status++;
                    p.length++;
                }
            } else {
                for (Pair p : pairList) {
                    if (p.status == 2) {
                        continue;
                    }
                    p.length++;
                }
            }
        }

        int minLength = 101;
        for (Pair p : pairList) {
            if (p.status == 2) {
                if (p.length < minLength) {
                    minLength = p.length;
                }
            }
        }
        if (minLength == 101) {
            System.out.println(-1);
        } else {
            System.out.println(minLength);
        }
    }
}