#include <bits/stdc++.h>
using namespace std;

using uint = unsigned int;
using ll = long long;

ll solve() {
    uint L, R;
    cin >> L >> R;

    if (L == 0 and R == 0) {
        return 0;
    }

    int log_l = (int)bit_width(L) - 1, log_r = (int)bit_width(R) - 1;

    if (log_l < log_r) {
        return (1LL << log_r) * ((1LL << log_r) - 1);
    } else {
        return -1;
    }
}

int main() {
    cin.tie(nullptr);
    ios::sync_with_stdio(false);

    int T;
    cin >> T;
    for (int _ = 0; _ < T; _++) {
        cout << solve() << '\n';
    }
}