#include <cstdio>
#include <cstring>
#include <algorithm>
#include <cassert>
#include <iostream>
#define mod 998244353

using namespace std;

typedef long long ll;

void checkmn(ll a, ll b, ll c, ll &mn) {
    if(a % c == b % c && c > 1 && (mn == -1 || mn > c)) mn = c;
}
void checkmx(ll a, ll b, ll c, ll &mx) {
    if(a % c == b % c && c > 1 && (mx == -1 || mx < c)) mx = c;
}
ll min_factor(ll x) {
    for(int i = 2; i <= 100000; i++) if(x % i == 0) return i;
    return x;
}
void solve() {
    ll a, b;
    scanf("%lld%lld", &a, &b);
    ll d = (a > b) ? a - b : b - a;
    if(d == 1 || d == 0 && a == 1) puts("-1 -1");
    else if(d == 0) printf("2 %lld\n", a);
    else printf("%lld %lld\n", min_factor(d), d);
}

int main() {
    int T;
    scanf("%d", &T);
    while(T--) {
        solve();
    }
}