using System;

namespace yukicoder
{
    class Program
    {
        static void Main(string[] args)
        {
            string s = Console.ReadLine();
            int count = 0;
            int ans = 0;
            int w = 0;

            for(int i = 0; i < s.Length; i++)
            {
                string a = s.Substring(i, 1);
                if (a == "c")
                {
                    count++;
                }
                else if (count > 0)
                {
                    count++;
                }
                if (count > 0 && a == "w"&&w==0)
                {
                    w ++;
                }else if (w == 1 && a == "w")
                {
                    ans = count;
                    break;
                }
            }
            if (ans == 0)
            {
                ans = -1;
            }
            Console.WriteLine(ans);
        }
    }
}