#include<cstdio>
#include<cstring>
#include<algorithm>
using namespace std;
const int INF=1000000000;
int main()
{
    int T;
    scanf("%d",&T);
    for(int tmn=1;tmn<=T;tmn++)
    {
        int a,b;
        scanf("%d %d",&a,&b);
        if(a<b)    swap(a,b);
        int delta=a-b,ans1=delta,ans2=delta;
        if(delta==1)
        {
            printf("-1 -1\n");
            continue;
        }
        else if(delta==0)
        {
            if(a!=1)
                printf("2 %d\n",a);
            else
                printf("-1 -1\n");
            continue;
        }
        for(int i=2;1LL*i*i<=delta;i++)
            if(delta%i==0)
            {
                ans1=min(ans1,min(i,delta/i));
                ans2=max(ans2,max(i,delta/i));
            }
        printf("%d %d\n",ans1,ans2);
    }
    return 0;
}