using System;
using System.Collections.Generic;

class Program
{
    static void Main()
    {
        int N = int.Parse(Console.ReadLine());
        string S = Console.ReadLine();

        var list = new List<int>();

        for (int k = 2; k <= N; k++)
        {
            if (S[k - 2] == 'x' && S[k - 1] == 'o')
            {
                list.Add(k);
            }
        }

        Console.WriteLine(list.Count);
        if (list.Count > 0)
            Console.WriteLine(string.Join(" ", list));
    }
}