#include<bits/stdc++.h>
using namespace std;

typedef long long ll;
typedef unsigned long long ull;
typedef double db;
typedef pair <int,int> Pii;
#define reg register
#define mp make_pair
#define pb push_back
#define Mod1(x) ((x>=P)&&(x-=P))
#define Mod2(x) ((x<0)&&(x+=P))
#define rep(i,a,b) for(int i=a,i##end=b;i<=i##end;++i)
#define drep(i,a,b) for(int i=a,i##end=b;i>=i##end;--i)
template <class T> inline void cmin(T &a,T b){ ((a>b)&&(a=b)); }
template <class T> inline void cmax(T &a,T b){ ((a<b)&&(a=b)); }

char IO;
template <class T=int> T rd(){
    T s=0; int f=0;
    while(!isdigit(IO=getchar())) f|=IO=='-';
    do s=(s<<1)+(s<<3)+(IO^'0');
    while(isdigit(IO=getchar()));
    return f?-s:s;
}

bool Mbe;
const int N=1e6+10,INF=1e9+10,P=998244353;

int a,b,c,L,R;

void Check(int m){
    if(m>1 && m<=max(a,b) && a%m==b%m) cmax(R,m),cmin(L,m);
}

bool Med;
int main(){ 
    rep(_,1,rd()) {
        a=rd(),b=rd(),c=abs(a-b);
        if(a==b) {
            if(a==1) puts("-1 -1");
            else printf("2 %d\n",a);
            continue;
        }
        L=1e9,R=-1;
        rep(i,1,sqrt(c)+10) if(c%i==0) Check(i),Check(c/i);
        if(R==-1) puts("-1 -1");
        else printf("%d %d\n",L,R);
    }
}