using System;
using System.Collections.Generic;
using System.Linq;

namespace _345
{
    class Program
    {
        static void Main(string[] args)
        {
            var s = Console.ReadLine();
            var sizes = new List<int>();
            for (int x1 = 0, len = s.Length; x1 < len; x1++)
            {
                if (s[x1] != 'c')
                {
                    continue;
                }

                var x2 = s.IndexOf('w', x1 + 1);
                if (x2 == -1)
                {
                    continue;
                }

                var x3 = s.IndexOf('w', x2 + 1);
                if (x3 == -1)
                {
                    continue;
                }

                sizes.Add(x3 - x1 + 1);
            }

            if (sizes.Any())
            {
                Console.WriteLine(sizes.Min());
            }
            else
            {
                Console.WriteLine(-1);
            }
        }
    }
}