#include <bits/stdc++.h>
using namespace std;
#include <atcoder/all>
using namespace atcoder;
using ll = long long;
int n;
string s;

void solve(){
    vector<int> ans;
    for(int i = 0;i<n-1;i++){
        if(s[i]=='x'&&s[i+1]=='o'){
            ans.push_back(i+2);
        }
    }
    cout<<ans.size()<<endl;
    for(int i = 0;i<ans.size();i++){
        cout<<ans[i]<<' ';
    }
    cout<<endl;
}

signed main(){
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    cin >> n >> s;
    solve();
}