// Problem: E. Boring Segments
// Contest: Codeforces - Educational Codeforces Round 112 (Rated for Div. 2)
// URL: http://codeforces.com/contest/1555/problem/E
// Memory Limit: 256 MB
// Time Limit: 3000 ms
// 
// Powered by CP Editor (https://cpeditor.org)

#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
typedef pair<ll, ll>PLL;
typedef pair<int, int>PII;
typedef pair<double, double>PDD;
#define I_int ll
inline ll read()
{
    ll x = 0, f = 1;
    char ch = getchar();
    while(ch < '0' || ch > '9')
    {
        if(ch == '-')f = -1;
        ch = getchar();
    }
    while(ch >= '0' && ch <= '9')
    {
        x = x * 10 + ch - '0';
        ch = getchar();
    }
    return x * f;
}
  
inline void out(ll x){
    if (x < 0) x = ~x + 1, putchar('-');
    if (x > 9) out(x / 10);
    putchar(x % 10 + '0');
}
  
inline void write(ll x){
    if (x < 0) x = ~x + 1, putchar('-');
    if (x > 9) write(x / 10);
    putchar(x % 10 + '0');
}
  
#define read read()
#define closeSync ios::sync_with_stdio(0);cin.tie(0);cout.tie(0)
#define multiCase int T;cin>>T;for(int t=1;t<=T;t++)
#define rep(i,a,b) for(int i=(a);i<=(b);i++)
#define repp(i,a,b) for(int i=(a);i<(b);i++)
#define per(i,a,b) for(int i=(a);i>=(b);i--)
#define perr(i,a,b) for(int i=(a);i>(b);i--)
ll ksm(ll a, ll b)
{
    ll res = 1;
    while(b)
    {
        if(b & 1)res = res * a ;
        a = a * a ;
        b >>= 1;
    }
    return res;
}

const int inf = 0x3f3f3f3f;
const int maxn=5e6+7,maxm=210000;


void solve(){
    ll a=read,b=read;
    if(b>a) swap(a,b);
    ll tmp=a-b;
    ll res_max=a-b,res_min=0;
    if(!tmp) res_max=a,res_min=2;
    rep(i,2,tmp/i){
        if(tmp%i==0){
            res_min=i;break;
        }
    }
    if(!res_min) res_min=tmp;
    if(res_min<=1||res_max<=1){
        printf("-1 -1\n");
        return ;
    }
    printf("%lld %lld\n",res_min,res_max);
}

int main(){
    int _=read;
    while(_--) solve();

    
    
    
    
    
    
    
    return 0;
}