#include <bits/stdc++.h>
#define mst(a,b) memset(a,b,sizeof(a))
#define lowbit(x) ((x)&(-x))
#define X first
#define Y second
#define lc o<<1
#define rc o<<1|1
using namespace std;
typedef long long LL;
typedef long long ll;
typedef unsigned long long ull;
typedef pair<int,int> pii;
typedef pair<double,double> pdd;
typedef pair<ll,ll> pll;
const int inf = 0x3f3f3f3f;
const ll INF = 0x3f3f3f3f3f3f3f3f;
const int maxn = 1000000+10;
const int maxm = 100000+10;
const int mod = 998244353;
const double eps = 1e-8;

bool notPrime[maxn];
int prime[maxn], cnt;
void init() {
    notPrime[1] = true;
    cnt = 0;
    int limit = sqrt(1e9) + 1;
    for (int i = 2; i <= limit; ++i) {
        if (!notPrime[i]) {
            for (int j = i * i; j <= limit; j += i) {
                notPrime[j] = true;
            }
            prime[cnt++] = i;
        }
    }
}

int cal(int val) {
    if (val == 1) {
        return val;
    }
    for (int i = 0; i < cnt; ++i) {
        if (val % prime[i] == 0) {
            return prime[i];
        }
    }
    return val;
}

int main() {
#ifdef local
    freopen("in.txt", "r", stdin);
    //freopen("out.txt", "w", stdout);
#endif
    ios::sync_with_stdio(0);
    cin.tie(0);cout.tie(0);
    init();
    int T; cin >> T;
    while (T--) {
        int a, b;
        cin >> a >> b;
        if (a < b) {
            swap(a, b);
        }
        if (a == b) {
            if (a == 1) {
                cout << -1 << " " << -1 << "\n";
            } else {
                cout << 2 << " " << a << "\n";
            }
            continue;
        }
        int mx = a - b;
        int mn = cal(a - b);
        if (mx < 2 || mn < 2) {
            mx = mn = -1;
        }
        cout << mn << " " << mx << "\n";
    }

    return 0;
}