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

class Program
{
    static void Main(string[] args)
    {
        string S = "waaichiwawaakarichiwawadaisuki";// Console.ReadLine();
        int wCnt = 0;
        string chk = "";
        List<int> cwwCntList = new List<int>();

        for (int i = 0; i < S.Length; i++)
        {
            if (S[i] != 'c') continue;

            wCnt = 0;
            chk = S.Substring(i + 1);
            for (int j = 0; j < chk.Length; j++)
            {
                if (chk[j] != 'w') continue;
                wCnt++;
                if (2 <= wCnt)
                {
                    cwwCntList.Add(j + 2);
                    break;
                }
            }
        }
        Console.WriteLine(cwwCntList.Count == 0 ? -1 : cwwCntList.Min());
    }
}