#include<bits/stdc++.h>
using namespace std;
int main(){
    int n;
    long long a,b,c,t,g,cmax,cmin;
    scanf("%d",&n);
    while(n--){
        cmax=cmin=-1;
        scanf("%lld%lld",&a,&b);
        if(a>b){
            c=a;
            a=b;
            b=c;
        }
        t=b-a;
        if(t==1){
            printf("-1 -1\n");
            continue;
        }    
        if(a==b){
            if(a==1)
            printf("-1 -1\n");
            else
            printf("2 %lld\n",a);
            continue;
        }
        cmax=t;
        cmin=cmax;
        for(int i=2;i<=(int)sqrt(t);i++){
            if(t%i==0){
                cmin=i;
                break;
            }
        }
        printf("%lld %lld\n",cmin,cmax);
    }
}