#include<bits/stdc++.h>
int n,a[1000005],t;
char res[1000005];
bool work(int l1,int r1,int l2,int r2) {
	for(int i=1;i<n;++i) {
		if(l1<=r1&&((l2<=r2&&a[l1]==a[l2])||(l1<r1&&a[l1]==a[r1]))) {
			if(l1<r1&&a[l1]==a[r1]){++l1; --r1;res[i]='L'; res[2*(n-1)-i+1]='L';}
			else{++l1; ++l2;res[i]='L'; res[2*(n-1)-i+1]='R';}
		}
		else if(l2<=r2&&((l1<=r1&&a[r2]==a[r1])||(l2<r2&&a[l2]==a[r2]))) {
			if(l2<r2&&a[l2]==a[r2]) {++l2; --r2;res[i]='R';res[2*(n-1)-i+1]='R';}
			else{--r2; --r1;res[i]='R'; res[2*(n-1)-i+1]='L';}
		}
		else return 0;
	}
	return 1;
}
int main(){
	cin>>t;
	while(t--) {
		cin>>n;int p1=-1,p2=-1; 
		for(int i=1;i<=2*n;++i)cin>>a[i];
		for(int i=1;i<=2*n+1;++i) res[i]=0;
		for(int i=2;i<=2*n;++i) {if(a[1]==a[i]) {p1=i; break;}}
		for(int i=1;i<2*n;++i) {if(a[2*n]==a[i]) {p2=i; break;}}
		if(work(2,p1-1,p1+1,2*n)) {printf("L%sL\n",res+1);}
		else if(work(1,p2-1,p2+1,2*n-1)) {printf("R%sL\n",res+1);}
		else printf("-1\n");
	}
	return 0;
}