class Program
{
    static void Main(string[] args)
    {
        string str = Console.ReadLine();
        int cwwCount = 0;
        bool cFlg = false;
        int wCount = 0;
        for(int i = 0; i < str.Length; i++)
        {
            if (str[i] != 'c' && !cFlg)
            {
                continue;
            }
            cwwCount++;
            if (str[i] == 'c')
            {
                cFlg = true;
                cwwCount = 1;
                wCount = 0;
                continue;
            }
            if (str[i] == 'w' )
            {
                wCount++;
                if(wCount == 2)
                {
                    break;
                }
            }
            
        }
        if(cwwCount == 0 || cwwCount != 0 && wCount != 2)
        {
            Console.WriteLine(-1);
        }
        else
        {
            Console.WriteLine(cwwCount); 
        }

    }
}