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

int main() {
    int n;
    string s;
    cin >> n >> 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() << endl;
    for (int x : ans) {
        cout << x << " ";
    }
    cout << endl;
}