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

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        ArrayList<Character> ch = new ArrayList<Character>();
        String str = sc.next();
        for (char c : str.toCharArray())
            ch.add(c);
        int n = -1;
        int cnt = 0;
        int size = 0;
        
        for (int i = 0; i < ch.size(); i++) {
            if (cnt == 3) break;
            switch (cnt) {
                case 0:
                    if (ch.get(i) == 'c') { cnt++; size++; };
                    break;
                case 1:
                case 2:
                    if (ch.get(i) == 'w') cnt++;
                    size++;
                    break;
            }
        }
        if (cnt == 3) System.out.printf("%d\n", size);
        else System.out.println("-1");
    }
}