C

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

int main() {
    int t;
    cin>>t;

    while(t--){
        int n;
        string s;
        cin>>n>>s;

        vector<int> ans;

        for(int i=0; i<n; i+=2){
            if(s[i] != s[i+1]){
                if(ans.size()==0 || s[ans.back()]==s[i+1])
                    ans.push_back(i);
                else
                    ans.push_back(i+1);
            }
        }

        cout<<ans.size()<<"\n";
        for(auto e: ans)    cout<<e+1<<" ";
        cout<<"\n";
    }
}