#include <iostream>
#include <deque>
#include <cstring>
#include <algorithm>

using namespace std;

const int N = 1000005;

int arr[N], brr[N], crr[N], n;

bool calc(char op) {
    deque<int> a, b;
    string out, append;
    out.push_back(op);
    append.push_back('L');
    if (op == 'L') {
        for (int i = 2; i < crr[1]; i++) a.push_back(i);
        for (int i = n; i > crr[1]; i--) b.push_back(i);
    } else {
        for (int i = 1; i < crr[n]; i++) a.push_back(i);
        for (int i = n - 1; i > crr[n]; i--) b.push_back(i);
    }
    while (!a.empty() || !b.empty()) {
        int x1 = !a.empty() ? a.front() : 0;
        int x2 = !b.empty() ? b.front() : 0;
        int y1 = !a.empty() ? a.back() : 0;
        int y2 = !b.empty() ? b.back() : 0;
        if (crr[x1] == y1) {
            out.push_back('L');
            append.push_back('L');
            a.pop_front();
            a.pop_back();
        } else if (crr[x1] == y2) {
            out.push_back('L');
            append.push_back('R');
            a.pop_front();
            b.pop_back();
        } else if (crr[x2] == y1) {
            out.push_back('R');
            append.push_back('L');
            b.pop_front();
            a.pop_back();
        } else if (crr[x2] == y2) {
            out.push_back('R');
            append.push_back('R');
            b.pop_front();
            b.pop_back();
        } else {
            return false;
        }
    }
    reverse(append.begin(), append.end());
    out += append;
    cout << out << endl;
    return true;
}

int main() {
    int T;
    cin >> T;

    while (T--) {
        cin >> n;
        memset(brr, 0, sizeof brr);
        n *= 2;
        crr[0] = -1;
        for (int i = 1; i <= n; i++) {
            cin >> arr[i];
            if (brr[arr[i]]) {
                crr[brr[arr[i]]] = i;
                crr[i] = brr[arr[i]];
            } else {
                brr[arr[i]] = i;
            }
        }
        if (!calc('L') && !calc('R')) cout << -1 << endl;
    }
}