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

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

    int T; cin >> T;
    while(T--){
        int L,R; cin >> L >> R;
        if(R == 0){cout << "0\n"; continue;}
        for(int d=30; d--;) if(R&(1<<d)){
            if(L<(1<<d)) cout << (1LL<<d)*((1<<d)-1) << "\n";
            
            else cout << "-1\n";
            break;
        }
    }
}