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

int main() {
    ios::sync_with_stdio(false);
    cin.tie(0);
    int T;
    cin >> T;
    while(T--){
        int l, r;
        cin >> l >> r;
        if(r == 0){
            cout << "0\n";
            continue;
        }
        if(l != 0 && __lg(l) == __lg(r)){
            cout << "-1\n";
            continue;
        }
        int b = 1 << __lg(r);
        cout << (long long)(b) * (b - 1) << '\n';
    }
}