#include<cstdio>
#include<iostream>
#include<algorithm>
#include<cstring>
#include<cmath>
#include<stack>
#include<queue>
#define ll long long
#define uint unsigned int
#define ull unsigned long long
#define re register
using namespace std;
const ll N=5e5+10;
const ll Z=1e9+7;

inline ll read()
{
    long long s=0,w=1;
    char ch=getchar();
    while(ch<'0'||ch>'9')
    {
        if(ch=='-') w=-1;
        ch=getchar();
    }
    while(ch>='0'&&ch<='9')
    {
        s=s*10+ch-'0';
        ch=getchar();
    }
    return s*w;
}

ll n,m;

int main()
{
#ifndef ONLINE_JUDGE
    freopen("q.in","r",stdin);
    freopen("q.out","w",stdout);
#endif
    ll T=read();
    while(T--)
    {
        scanf("%lld%lld",&n,&m);
        bool flag=0;
        if(n>m) swap(n,m);
        if(n==m)
        {
            if(n==1) cout<<-1<<" "<<-1<<endl;
            else cout<<2<<" "<<m<<endl;
            continue;
        }
        if(n==1&&m==1||(m-n)<2) 
        {
            cout<<-1<<" "<<-1<<endl;
            continue;
        }
        if(m-n==2) 
        {
            cout<<2<<" "<<m-n<<endl;
            continue;
        }
        for(ll i=2;i<=sqrt(m-n);++i)
        {
            if((m-n)%i==0)
            {
                cout<<i<<" "<<m-n<<endl;
                flag=1;
                break;
            }
        }
        if(!flag) cout<<m-n<<" "<<m-n<<endl;
    }
    return 0;
}