#include <bits/stdc++.h>
using namespace std;
using ll = long long;

template<class T> istream& operator >> (istream& is, vector<T>& vec) {
    for(T& x : vec) is >> x;
    return is;
}

template<class T> ostream& operator << (ostream& os, const vector<T>& vec) {
    if(vec.empty()) return os;
    os << vec[0];
    for(auto it = vec.begin(); ++it != vec.end(); ) os << ' ' << *it;
    return os;
}

int main(){
    ios::sync_with_stdio(false);
    cin.tie(0);
    int n;
    string s;
    cin >> n >> s;
    vector<int> ans;
    for(int i = 0; i + 1 < s.size(); i++){
        if(s[i] == 'x' && s[i + 1] == 'o') ans.push_back(i + 2);
    }
    cout << ans.size() << '\n' << ans << '\n';
}