#include <bits/stdc++.h>
using namespace std;
#include <atcoder/all>
using namespace atcoder;
#define ll long long
#define rep(i, n) for (ll i = 0; i < (ll)(n); i++)
using mint = modint998244353;
const int dx[4]={0,1,0,-1};
const int dy[4]={1,0,-1,0};

int n;
string s;
int main(){
    cin >> n >> s;
    vector<int>ans;
    rep(i,n-1){
        if(s[i]=='x'&&s[i+1]=='o')ans.push_back(i+2);
    }
    cout<<ans.size()<<endl;
    rep(i,ans.size())cout<<ans[i]<<" ";
    cout<<endl;
}