#include <algorithm>
#include <cmath>
#include <cstdio>
#include <cstring>
#include <iostream>
#include <list>
#include <map>
#include <queue>
#include <random>
#include <set>
#include <stack>
#include <string>
#include <unordered_map>
#include <unordered_set>
#include <vector>

//#include <atcoder/convolution>
//#include <atcoder/modint> 
//using Modint = atcoder::modint998244353;

using namespace std;
typedef long long ll;

void ex_gcd(ll a, ll b, ll &d, ll &x, ll &y) {
  if (!b) {
    d = a;
    x = 1;
    y = 0;
  } else {
    ex_gcd(b, a % b, d, y, x);
    y -= a / b * x;
  }
}
ll inv(ll a, ll n) {
  ll d, x, y;
  ex_gcd(a, n, d, x, y);
  return d == 1 ? (x % n + n) % (n / d) : -1;
}
ll gcd(ll x, ll y) {
  if (y == 0) return x;
  return gcd(y, x % y);
}

int gcd(int x, int y) {
  if (y == 0) return x;
  return gcd(y, x % y);
}

const int maxn = 10005;
const int mod = 998244353;



int main() {
#ifdef suiyuan2009
  freopen("/Users/suiyuan2009/CLionProjects/icpc/input.cpp", "r", stdin);
  freopen("/Users/suiyuan2009/CLionProjects/icpc/output.cpp", "w", stdout);
#endif
  int T;
  cin>>T;
  while(T--){
    int x,y;
    cin>>x>>y;
    if(x<y)swap(x,y);
    if(x==y){
      if(x==1)cout<<-1<<" "<<-1<<endl;
      else cout<<2<<" "<<x<<endl;
    } else {
      int tt = x - y;
      int mi = -1, mx = -1;
      for(int i=1;i*i<=tt;i++){
        if(tt%i==0){
          int tmp = i;
          if(tmp>=2&&tmp<=x){
            if(mi==-1||mi>tmp)mi = tmp;
            mx = max(mx, tmp);
          }
          tmp = tt/i;
          if(tmp>=2&&tmp<=x){
            if(mi==-1||mi>tmp)mi = tmp;
            mx = max(mx, tmp);
          }
        }
      }
      cout<<mi<<" "<<mx<<endl;
    }
  }
  return 0;
}