#pragma GCC optimize("Ofast")
#include <bits/stdc++.h>
#define ud unsigned int
#define ll long long
#define ull unsigned long long
#define MAX_INF 0x3f
#define MAX_INF_VAL 0x3f3f3f3f
#define MAX_INF_VAL_LL 0x3f3f3f3f3f3f3f3f
//#define pi 3.141592653589
#define eps 1e-9
#define F(x) ((x)/3+((x)%3==1?0:tb))
#define G(x) ((x)<tb?(x)*3+1:((x)-tb)*3+2)
//#define p 2173412051LL
//#define sz 2

using namespace std;

template< typename T > void read( T &x ) {
    x = 0;
    char ch = getchar();
    ll f = 1;
    while( !isdigit( ch ) ) {
        if( ch == '-' )
        f *= -1;
        ch = getchar();
    }
    while( isdigit( ch ) ) {
        x = x * 10 + ch - 48;
        ch = getchar();
    }
    x *= f;
}

struct custom_hash {
    static uint64_t splitmix64( uint64_t x ) {
        x += 0x9e3779b97f4a7c15;
        x = ( x ^ ( x >> 30 ) ) * 0xbf58476d1ce4e5b9;
        x = ( x ^ ( x >> 27 ) ) * 0x94d049bb133111eb;
        return x ^ ( x >> 31 );
    }

    size_t operator() ( uint64_t x ) const {
        static const uint64_t FIXED_RANDOM = chrono::steady_clock::now().time_since_epoch().count();
        return splitmix64( x + FIXED_RANDOM );
    }
};

int main() {
    ios::sync_with_stdio( false );
    cin.tie( 0 ), cout.tie( 0 );
    int t;
    cin >> t;
    while( t-- ) {
        int n, m;
        cin >> n >> m;
        if( n == m ) {
            if( n == 1 )
                cout << -1 << ' ' << -1 << '\n';
            else
                cout << 2 << ' ' << n << '\n';
            continue;
        }
        if( n < m )
            swap( n, m );
        int ma = -1, mi = 2e9;
        int tmp = n - m;
        for( int i = 1; i * i <= tmp; ++i ) {
            if( tmp % i )
                continue;
            if( i > 1 && n % i == m % i ) {
                ma = max( ma, i );
                mi = min( mi, i );
            }
            int fk = tmp / i;
            if( fk > 1 && n % fk == m % fk ) {
                ma = max( ma, fk );
                mi = min( mi, fk );
            }
        }
        if( mi == 2e9 )
            mi = -1;
        cout << mi << ' ' << ma << '\n';
    }
    return 0;
}