#include <bits/stdc++.h>
using namespace std;
#define N 1000005
#define int long long
int n,m;
char ans[N];
int x[N];
void init(){
	fill(ans,ans + N,'L');
}
bool work(deque<int> a,deque<int> b){
	int step = 1;
	while(step <= n){
		if (a.size() > 1 && a.front() == a.back()){
			a.pop_front();
			a.pop_back();
		} else if (a.size() && b.size() && a.front() == b.front()){
			a.pop_front();
			ans[m - step + 1] = 'R';
			b.pop_front();
		} else if (a.size() && b.size() && a.back() == b.back()){
			a.pop_back();
			ans[step] = 'R';
			b.pop_back();
		} else if (b.size() > 1 && b.front() == b.back()){
			ans[step] = ans[m - step + 1] = 'R';
			b.pop_front();
			b.pop_back();
		} else  return false;
		step++;
	}
	for (int i = 1;i <= m;i++) cout << ans[i];
	cout << endl;
	return true; 
}
void solve(){
	init();	
	deque<int> a,b,c,d;
	cin >> n;
	m = 2 * n;
	for (int i = 1;i <= m;i++){
		cin >> x[i];
		if (i < 3) a.push_back(x[i]);
	} 
	for (int i = 3;i <= m;i++){
		if (a.front() != a.back()) a.push_back(x[i]);
		else b.push_back(x[i]);
	}
	d.push_front(x[m]);
	d.push_front(x[m - 1]);
	for (int i = m - 2;i > 0;i--){
		if (d.front() != d.back()) d.push_front(x[i]);
		else c.push_front(x[i]);
	}
	c.push_back(d.front());
	d.pop_front();
	if (!work(a,b) && !work(c,d)) cout << -1 << endl;
}
signed main(){
	int t;
	cin >> t;
//	freopen("out.txt","w",stdout);
	while(t--) solve();
	return 0;
}