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

ll gcd(ll a,ll b){
    return b == 0 ? a : gcd(b,a%b);
}

ll lcm(ll a,ll b){
    return a * b / gcd(a, b);
}

ll ksm(ll x,ll n,ll mod){
    ll res = 1;
    x = x % mod;
    while(n > 0){
        if(n & 1) res = res * x % mod;
        x = x * x % mod;
        n >>= 1;
    }
    return res;
}

ll fac(int n){
    ll f = 1;
    for(int i=n;i>0;i--) f *= i;
    return f;
}

ll C(int n, int m){
    return fac(n) / (fac(n - m) * fac(m));
}

int main(){

    int T;
    scanf("%d", &T);
    ll a, b, c;
    ll minn, maxx;
    while(T--){
        minn = -1;
        maxx = -1;
        scanf("%lld %lld", &a, &b);

        if(a == b){
            if(a == 1){
                printf("-1 -1\n");
            }else{
                printf("2 %lld\n", b);
            }
            continue;
        }

        if(a > b) swap(a, b);

        if(b - a == 1){
            printf("-1 -1\n");
            continue;
        }

        maxx = b - a;
        minn = maxx;
        for(int i=2;i*i<=maxx + 50;i++){
            if((a % i) == (b % i)){
                minn = i;
                break;
            }
        }

        printf("%lld %lld\n", minn, maxx);

    }

    /*ll a, b;
    while(1){
    scanf("%lld %lld", &a, &b);

        for(int i=2;i<=b;i++){
            if((a % i) == (b % i)){
                cout<<i<<endl;
            }
        }
    }*/


    return 0;
}