using System;
using System.Text;
using System.Text.RegularExpressions;

class Program {
    static void Main(string[] args) {
        var s = Console.ReadLine();

        var match = Regex.Match(s, @"c.*?w.*?w");
        if (match.Success)
            Console.WriteLine(match.Length);
        else
            Console.WriteLine("-1");

#if DEBUG
        Console.ReadLine();
#endif
    }
}