#include <bits/stdc++.h>

int main() {
    std::cin.tie(nullptr)->sync_with_stdio(false);

    int t;
    std::cin >> t;
    void solve();
    while (t--) solve();

    return 0;
}

void solve() {
    int l, r;
    std::cin >> l >> r;
    if (l == r) {
        if (l == 1) std::cout << "1\n";
        else std::cout << "-1\n";
    } else if ((r - l) & 1) {
        for (int i = l; i <= r; i++) {
            std::cout << (i == r ? l : i + 1) << " \n"[i == r];
        }
    } else if (l & 1) {
        std::cout << l + 1 << ' ' << l + 2 << ' ' << l << " \n"[r - l == 2];
        for (int i = l + 3; i <= r; i++) {
            std::cout << (i == r ? l + 3 : i + 1) << " \n"[i == r];
        }
    } else {
        std::cout << "-1\n";
    }
}