import java.util.Scanner;
public class Main{
	private static Scanner sc=new Scanner(System.in);
	public static void main(String args[])throws Exception{
		String s=sc.nextLine();
		s=s.substring(s.lastIndexOf('c'),s.lastIndexOf('w')+1);
		if(s.lastIndexOf('w') == s.indexOf('w')){
			System.out.println(-1);
		}else{
			System.out.println(s.length());
		}
	}
}