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#include <bits/stdc++.h>
using namespace std;
using ll = long long;
typedef pair<ll, ll> pir;
const int N = 1e6 + 5;
int a[N * 2], n, seq[N];
pir pos[N];  // first表示左边的位置,second表示右边的位置
string construct_sequence(int start_pos, char start_char) {
    string ans;
    ans += start_char;
    int l1, r1, l2, r2;
    if (start_char == 'L') {
        l1 = 1, r1 = 2 * n + 1;
        l2 = pos[a[1]].second, r2 = l2;
    } else {
        l1 = 0, r1 = 2 * n;
        l2 = pos[a[2 * n]].first, r2 = l2;
    }
    while (l1 < l2 && r2 < r1) {
        if (r2 - l2 + 1 == n) break;
        if (l1 + 2 < l2 && a[l1 + 1] == a[l2 - 1]) {
            l1++, l2--, ans += 'L';
        } else if (l1 + 1 < l2 
			&& r2 + 1 < r1 && a[l1 + 1] == a[r2 + 1]) {
            l1++, r2++, ans += 'L';
        } else if (r1 - 2 > r2 
			&& a[r1 - 1] == a[r2 + 1]) {
            r1--, r2++, ans += 'R';
        } else if (r1 - 1 > r2 
			&& l2 - 1 > l1 && a[r1 - 1] == a[l2 - 1]) {
            r1--, l2--, ans += 'R';
        } else {
            return "-1";
        }
    }
    int temp_l1 = 0, temp_r1 = 2 * n + 1;
    for (int i = 1; i <= n; i++) {
        if (ans[i - 1] == 'L')
            seq[i] = a[++temp_l1];
        else
            seq[i] = a[--temp_r1];
    }
    int p = n;
    while (l2 < r2) {
        if (a[r2] != seq[p])
            l2++, ans += 'L';
        else
            r2--, ans += 'R';
        --p;
    }
    ans += 'L';
    return ans;
}

void solve() {
    cin >> n;
    for (int i = 1; i <= n * 2; i++) pos[i] = {0, 0};
    for (int i = 1; i <= 2 * n; i++) {
        cin >> a[i];
        if (pos[a[i]].first)
            pos[a[i]].second = i;
        else
            pos[a[i]].first = i;
    }
    string ansL = construct_sequence(1, 'L');
    if (ansL != "-1") {
        cout << ansL << '\n';
        return;
    }
    string ansR = construct_sequence(2 * n, 'R');
    if (ansR != "-1")
        cout << ansR << '\n';
    else
        cout << "-1"<<endl;
}
int main() {
    int t;
    cin >> t;
    while (t--) solve();
}