#include <iostream>
#include <vector>

using namespace std;
using ll = long long;

constexpr int iINF = 1'000'000'000;
constexpr ll llINF = 1'000'000'000'000'000'000;

int main () {
    int N; cin >> N;
    string S; cin >> S;

    vector<int> ans;
    for (int i = 1; i < N; i++) {
        if (S[i - 1] == 'x' && S[i] == 'o') ans.push_back(i + 1);
    }

    cout << ans.size() << "\n";
    for (int i = 0; i < ans.size(); i++) cout << ans[i] << (i == ans.size() - 1 ? "" : " ");
    cout << "\n";
}