#include <bits/stdc++.h>
using namespace std;
using ll = long long;
#define rep(i, n) for (int i = 0; i < (int)(n); i++)

int main() {
    cin.tie(nullptr);
    ios_base::sync_with_stdio(false);
    int t;
    cin >> t;
    while (t--) {
        ll l, r;
        cin >> l >> r;
        ll b = 1;
        ll R = r;
        while (R != 1) {
            R /= 2;
            b *= 2;
        }
        if (l <= b - 1) {
            cout << (b - 1) * b << endl;
        } else {
            cout << -1 << endl;
        }
    }
    return 0;
}