#include <bits/stdc++.h>
using namespace std;
typedef unsigned int ui;
typedef long long ll;
typedef unsigned long long ull;
typedef double db;
typedef long double ldb;
#define range(x) (x).begin(),(x).end()
std::mt19937 rnd(chrono::steady_clock::now().time_since_epoch().count());
inline int sj(int n)
{
    unsigned int x=rnd();
    return x%n+1;
}
#define rand fst
template<typename typC> void read(register typC &x)
{
    register int c=getchar(),fh=1;
    while ((c<48)||(c>57))
    {
        if (c=='-') {c=getchar();fh=-1;break;}
        c=getchar();
    }
    x=c^48;c=getchar();
    while ((c>=48)&&(c<=57))
    {
        x=x*10+(c^48);
        c=getchar();
    }
    x*=fh;
}
template<typename typC> void read(register typC *a,int num)
{
    for (register int i=1;i<=num;i++) read(a[i]);
}
template<typename typC, typename... Args> void read(typC &first, Args& ... args) {
    read(first);
    read(args...);
}
template<typename typC> void write(register typC x)
{
    if (x<0) putchar('-'),x=-x;
    static int st[100];
    register int tp=1;
    register typC y;st[1]=x%10;x/=10;
    while (x) y=x/10,st[++tp]=x-y*10,x=y;++tp;
    while (--tp) putchar(st[tp]|48);
}
template<typename typC> void write(register typC *a,register int num)
{
    if (num<=0) puts("");
    for (register int i=1;i<=num;i++) write(a[i]),putchar(i==num?10:32);
}
template<typename typC> typC ab(register typC x)
{
    if (x<0) return -x;
    return x;
}
#define space(x) write(x),putchar(32)
#define enter(x) write(x),putchar(10)
#define debug(x,y) printf("%s: ",#x),write(x,y)
const int p=998244353;
const db eps=1e-9;
inline void inc(register int &x,const int y)
{
    if ((x+=y)>=p) x-=p;
}
inline void dec(register int &x,const int y)
{
    if ((x-=y)<0) x+=p;
}
inline int ksm(register int x,register int y)
{
    register int r=1;
    while (y)
    {
        if (y&1) r=(ll)r*x%p;
        x=(ll)x*x%p;
        y>>=1;
    }
    return r;
}
priority_queue<int> ONLYYFORRCOPYY;
priority_queue<int,vector<int>,greater<int> > ONLYYFORRCOPYY__;
struct Q
{
    int u,v;
    Q(int a=0,int b=0):u(a),v(b){}
    bool operator<(const Q &o) const {return v<o.v;}
};
const int N=1e6+2,M=1e6+2,inf=1e9;
char s[N];
int a[N],b[N];
int T,n,m,c,i,j,k,x,y,z,ans,la,ksiz,ks;
int main()
{
    //ios::sync_with_stdio(false);cin.tie(0);cout.tie(0);
    cout<<setiosflags(ios::fixed)<<setprecision(15);
    T=1;
    read(T);
    while (T--)
    {
        read(n,m);
        if (n>m) swap(n,m);
        n=m-n;
        if (n==1) {puts("-1 -1");continue;}
        if (n==0)
        {
            if (m==1) puts("-1 -1"); else printf("%d %d\n",2,m);
        }
        else
        {
            m=sqrt(n);
            for (i=2;i<=m;i++) if (n%i==0) break;
            if (i<=m) printf("%d %d\n",i,n); else printf("%d %d\n",n,n);
        }
    }
}