萌新刚学OI，不懂为何CE..

#include<bits/stdc++.h>
#define ll long long
#define pii pair<int,int>
#define F first
#define S second
#define mp make_pair
#define vi vector<int>
#define pb push_back

using namespace std;
const int N=2e5+5;
int T,n,x[N];
void solve()
{
	cin>>n;
	for(int i=0;i<2*n;i++)
		cin>>x[i];
	for(int i=0;i<(1<<(2*n));i++)
	{
		deque<int>q;q.clear();
		vi v;v.clear();
		for(int j=0;j<2*n;j++)q.pb(x[j]);
		for(int j=0;j<2*n;j++)
		{
			if((i>>(2*n-j))&1){
				v.pb(q.back());
				q.pop_back();
			}else{
				v.pb(q.front());
				q.pop_front();
			}
		}
		bool ok=true;
		for(int j=0;j<2*n;j++)
			if(v[j]!=v[2*n-j-1])
			{
				ok=false;
				break;
			}
		if(ok)
		{
			for(int j=0;j<2*n;j++)
			{
				if((i>>(2*n-j))&1)
					cout<<"R";
				else
					cout<<"L";
			}
			cout<<"\n";
			return ;
		}
	}
	cout<<"-1\n";
	return;
}
int main()
{
//	freopen("palin.in","r",stdin);
//	freopen("palin.out","w",stdout);
	cin>>T;
	while(T--)solve();
	return 0;
}