#include<bits/stdc++.h>
using namespace std;
int main(){
	int s; cin >> s;
	string str; cin >> str;
	vector<int> ans;
	for(int i = 0; i < s - 1; i++){
		if(str[i] == 'x' && str[i + 1] == 'o') ans.push_back(i + 2);
	}
	cout << ans.size() << endl;
	for(auto x : ans) cout << x << " ";
	cout << endl;
	return 0;
}