A

#include <bits/stdc++.h>

using namespace std;

#define ll     long long
#define _test   int _TEST; cin>>_TEST; while(_TEST--)
#define pb     push_back
#define ppb    pop_back


int main()
{
    _test
    {
        int n;
        string s;
        cin>>n>>s;

        reverse(s.begin(), s.end());
        string ans = "";

        while(s.size())
        {
            ans += s.back();
            s.ppb();

            while(s.back() != ans.back())
                s.ppb();

            s.ppb();
        }

        cout<<ans<<"\n";
    }
}