#define _USE_MATH_DEFINES
#include  <cmath>
#include <cstdio>
#include <vector>
#include <iostream>
#include <algorithm>
#include <string>
#include<math.h>
#include<iomanip>
#include<stdio.h>
#include <stdlib.h>
#include<stdio.h>
#include <queue>
#include<map>
#include <sstream>
#include<set>
#include<stack>
#include<time.h>
#include <sys/types.h>
#include <tuple>
#include <numeric>


typedef long long int ll;
//#include<bits/stdc++.h>


using namespace std;



int main()
{

    int Q;
    Q = 1;
//    cin >> Q;

    while (Q--) {
        int n;
        cin >> n;
        string p;
        cin >> p;
        vector<int>ans;
        bool f = 0,r=0;
        for (int i = 0; i < n-1; i++) {
            if (p[i] == 'x') {
                if (p[i + 1] == 'x')continue;
                ans.push_back(i + 2);
               
            }
            
        }
        cout << ans.size() << endl;
        for (int i =0 ; i< ans.size(); i++) {
            if (i)cout << " ";
            cout << ans[i];
            
        }
        cout << endl;
    }

    return 0;
}