using System;

class Program
{
    static void Main(string[] args)
    {
        var input = Console.ReadLine();
        var c_idx = input.IndexOf('c');
        var w_f_idx = input.IndexOf('w');
        var w_l_idx = input.LastIndexOf('w');
        if (c_idx >= 0 && w_f_idx > 0 && w_l_idx > 0)
        {
            if (c_idx < w_f_idx && w_f_idx < w_l_idx) Console.WriteLine((w_l_idx - c_idx) + 1);
        }
        else Console.WriteLine("-1");
    }
}