#include<bits/stdc++.h>
#define debug(x) cerr<<"\tDEBUG: "<<#x<<" = "<<(x)<<endl
using namespace std;
const int maxn=2e2+10,P=998244353;
int a,b;
int ans1,ans2;
void clear(){
    ans1=ans2=-1;
}
bool check(int x){
    return a%x==b%x&&x<=max(a,b);
}
void insert(int x){
    if(x!=1&&check(x)){
        if(ans1==-1){
            ans1=ans2=x;
        }else {
            ans1=min(ans1,x);
            ans2=max(ans2,x);
        }
    }
}
int main(){
    int QuQ;cin>>QuQ;
    while(QuQ--){
        cin>>a>>b;
        clear();
        if(a==1&&b==1){
            cout<<-1<<" "<<-1<<endl;
            continue;
        }
        if(a==b){
            cout<<2<<" "<<a<<endl;
            continue;
        }
        if(a<b)swap(a,b);
        if(a-b>=2)insert(a-b);
        int tmp=a-b;
        for(int i=1,ed=sqrt(tmp);i<=ed;i++){
            if(tmp%i==0){
                insert(i);
                insert(tmp/i); 
            }
        }
        cout<<ans1<<" "<<ans2<<endl;
    }
    return 0;
}
/*
1
4 4 2
1 2 1
2 4 0
1 3 0
3 4 0
*/