import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.StringTokenizer;

public class Main {

    static int N = 100000;
    static int[] pri = new int[N + 1];
    static boolean[] isprime = new boolean[N + 1];
    static int cnt = 0;


    public static void main(String[] args) {

        FastReader sc = new FastReader();

        int T = sc.nextInt();

        prime();

        while (T-- > 0) {
            int x = -1, y = -1;

            int a = sc.nextInt();
            int b = sc.nextInt();

            if(a == 1 && b == 1){
                System.out.println(x + " " + y);
                continue;
            }

            if (Math.abs(a - b) == 1) {
                System.out.println(x + " " + y);
                continue;
            }

            int mm = Math.min(a, b);
            for (int i = 0; i < cnt && pri[i] <= mm; i++) {
                if (a % pri[i] == b % pri[i]) {
                    x = pri[i];
                    break;
                }
            }

            if (a == b) {
                if(x == -1){
                    x = a;
                }
                y = a;
                System.out.println(x + " " + y);
                continue;
            }

            y =  Math.abs(a - b);
            if(x == -1){
                x = y;
            }
            System.out.println(x + " " + y);
        }
    }

    private static void prime() {
        isprime[0] = true;
        isprime[1] = true;
        for (int i = 2; i <= N; i++) {
            if (!isprime[i]) {
                pri[cnt++] = i;
            }
            for (int j = 0; j < cnt && i * pri[j] <= N; j++) {
                isprime[i * pri[j]] = true;
                if (i % pri[j] == 0) {
                    break;
                }
            }
        }
    }

    static class FastReader {
        BufferedReader br;
        StringTokenizer st;

        public FastReader() {
            br = new BufferedReader(
                    new InputStreamReader(System.in));
        }

        String next() {
            while (st == null || !st.hasMoreElements()) {
                try {
                    st = new StringTokenizer(br.readLine());
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            return st.nextToken();
        }

        int nextInt() {
            return Integer.parseInt(next());
        }

        long nextLong() {
            return Long.parseLong(next());
        }

        double nextDouble() {
            return Double.parseDouble(next());
        }

        String nextLine() {
            String str = "";
            try {
                str = br.readLine();
            } catch (IOException e) {
                e.printStackTrace();
            }
            return str;
        }

        int[] arrayIn(int n) throws IOException {
            int arr[] = new int[n];
            for (int i = 0; i < n; i++) {
                arr[i] = nextInt();
            }
            return arr;
        }
    }

    public static void printarr(int[] arr) {
        for (int i = 0; i < arr.length; i++) {
            System.out.print(arr[i] + " ");
        }
    }
}