using System;

namespace No345
{
    class Program
    {
        static void Main(string[] args)
        {
            int pointer = 0;
            int[] counter = new int[3];
            string word = "cww";
            string text = Console.ReadLine();

            foreach(char s in text)
            {
                if (word[pointer] == s)
                {
                    pointer++;
                    if (pointer == word.Length)
                        break;
                }
                counter[pointer]++;
            }

            int sum = 1;

            if (pointer == word.Length)
            {
                for (int i = 1; i < word.Length; i++)
                    sum += counter[i];
            }
            else
                sum = -1;

            Console.WriteLine(sum);
        }
    }
}