import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        try (Scanner scan = new Scanner(System.in)) {
            
            String S = scan.nextLine();
            int ans = 0;
            
            for(int i=0; i<S.length(); i++) {
                if(S.charAt(i) == 'c') {
                    int count = 0;
                    for(int j=i+1; j<S.length(); j++) {
                        if(S.charAt(j) == 'w') {
                            count++;
                        }
                    }
                    if(count >= 2) {
                        int tmp = 0;
                        for(int j=count-1; j>=1; j--) {
                            tmp += j;
                        }
                        ans += tmp;   
                    }
                }
            }
            if(ans == 0) {
                System.out.println(-1);
            } else {
                System.out.println(ans);
            }
        }
    }
}