import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.PrintWriter;

public class Main {
	public static void main(String[] args) throws Exception {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		int t = Integer.parseInt(br.readLine());
		PrintWriter pw = new PrintWriter(System.out);
		for (int z = 0; z < t; z++) {
			String[] sa = br.readLine().split(" ");
			int l = Integer.parseInt(sa[0]);
			int r = Integer.parseInt(sa[1]);

			int ml = Integer.highestOneBit(l);
			int mr = Integer.highestOneBit(r);
			if (ml == mr) {
				pw.println(-1);
			} else {
				long ans = (long) mr * (mr - 1);
				pw.println(ans);
			}
		}
		pw.flush();
		br.close();
	}
}