#include <bits/stdc++.h>
using namespace std;
using ll = long long;
#define rep(i, s, e) for (int i = (int)(s); i < (int)(e); ++i)
#define all(a) (a).begin(),(a).end()

int main() {
    cin.tie(nullptr);
    ios_base::sync_with_stdio(false);
    
    int N;
    string S;
    cin >> N >> S;
    
    vector<int> ans;
    rep(i, 0, N - 1) {
        if (S[i] == 'x' && S[i + 1] == 'o') ans.push_back(i + 2);
    }
    
    cout << ans.size() << '\n';
    rep(i, 0, ans.size()) cout << ans[i] << ' ';
    cout << '\n';
}