#include <bits/stdc++.h>

typedef long long LL;

#define FOR(i, a, b) for (int i = (a), i##_END_ = (b); i <= i##_END_; ++i)
#define DNF(i, a, b) for (int i = (a), i##_END_ = (b); i >= i##_END_; --i)

template <typename Tp> void in(Tp &x) {
  char ch = getchar(), f = 1; x = 0;
  while (ch != '-' && (ch < '0' || ch > '9')) ch = getchar();
  if (ch == '-') f = -1, ch = getchar();
  while (ch >= '0' && ch <= '9') x = x * 10 + ch - '0', ch = getchar();
  x *= f;
}

template <typename Tp> bool chkmax(Tp &x, Tp y) {return x >= y ? 0 : (x=y, 1);}
template <typename Tp> bool chkmin(Tp &x, Tp y) {return x <= y ? 0 : (x=y, 1);}
template <typename Tp> Tp Max(const Tp &x, const Tp &y) {return x > y ? x : y;}
template <typename Tp> Tp Min(const Tp &x, const Tp &y) {return x < y ? x : y;}

int T;

void divide(int x) {
  if (x == 1) {
    puts("-1 -1"); return;
  }
  int t = int(sqrt(x)) + 1;
  int low = x;
  FOR(i, 2, t) {
    if (x % i == 0) {
      low = i; break;
    }
  }
  printf("%d %d\n", low, x);
}

int main() {
  in(T); while (T--) {
    int a, b; in(a); in(b);
    if (a == b && a != 1) {
      printf("2 %d\n", Max(a, b));
    }
    else if (a == b && a == 1) {
      puts("-1 -1");
    }
    else 
      divide(Max(a, b) - Min(a, b));
  }
  return 0;
}