C

#include <bits/stdc++.h>

using namespace std;

#define _test   int _TEST; cin>>_TEST; while(_TEST--)

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

        int f = 0;

        for(int i=n-1; i>0; i-=2)
            f |= (s[i]==s[i-1]);

        if(f)       cout<<"NO\n";
        else        cout<<"YES\n";
    }
}