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

int main(){
  ll n;
  cin>>n;
  string s;
  cin>>s;
  vector<ll> ans;
  for(ll i=0;i<n-1;i++){
    if(s[i]=='x'&&s[i+1]=='o'){
      ans.push_back(i+2);
    }
  }
  cout<<ans.size()<<endl;
  for(ll a:ans){
    cout<<a<<" ";
  }
}