using System;
using System.Linq;

class Program
{
    static void Main(string[] args)
    {
        var input   = Console.ReadLine();
        var chArr   = input.ToCharArray();
        int first_c = 0;
        int first_w = 0;
        int last_w  = 0;
        int len     = 0;

        if (chArr.Count(x => x == 'c') >= 1 && chArr.Count(x => x == 'w') >= 2)
        {
            input = new string(chArr);
            first_c = input.IndexOf('c');
            first_w = input.IndexOf('w');
            last_w = input.LastIndexOf('w');

            len = (last_w - first_c) + 1;
            input = input.Substring(first_c, len);
            first_c = input.IndexOf('c');
            first_w = input.IndexOf('w');

            for (int i = first_w + 1; i <input.Length; i++)
            {
                if (input[i] == 'w')
                {
                    last_w = i;
                    break;
                }
            }
            input = input.Substring(0, last_w + 1);           
            Console.WriteLine(input.Length);
        }
        else Console.WriteLine("-1");


    }
}