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

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

    int T; cin >> T;
    while (T--) {
        ll L, R; cin >> L >> R;
        if (R == 0) {
            cout << "0\n";
        } else if (L > 0 && bit_width((unsigned)L) == bit_width((unsigned)R)) {
            cout << "-1\n";
        } else {
            int k = bit_width((unsigned)R) - 1;
            cout << (1LL << k) * ((1LL << k) - 1) << '\n';
        }
    }
}