#include <bits/stdc++.h>

using namespace std;
using ll = long long;

int main(){
    cin.tie(nullptr);
    ios_base::sync_with_stdio(false);

    int N;
    string S;
    vector<int> ans;
    cin >> N >> S;
    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 (auto x : ans) cout << x << " ";
    cout << endl;

    return 0;
}