t = int(input())
for i in range(t):
l, r = map(int, input().split())
if l * 2 > r:
print(-1, -1)
else:
print(l, l * 2)#include <bits/stdc++.h>
#define endl "\n";
#define ll long long
using namespace std;
int main()
{
ll t;
cin>>t;
while(t--) {
ll a, b;
cin>>a>>b;
if(b%a==0) {
cout<<a<<" "<<b<<endl
}
else {
if(b/a > 1) {
cout<<a<<" "<<a*2<<endl
}
else {
cout<<"-1 -1\n";
}
}
}
return 0;
}1169A - Circle Metro | 780C - Andryusha and Colored Balloons |
1153A - Serval and Bus | 1487C - Minimum Ties |
1136A - Nastya Is Reading a Book | 1353B - Two Arrays And Swaps |
1490E - Accidental Victory | 1335A - Candies and Two Sisters |
96B - Lucky Numbers (easy) | 1151B - Dima and a Bad XOR |
1435B - A New Technique | 1633A - Div 7 |
268A - Games | 1062B - Math |
1294C - Product of Three Numbers | 749A - Bachgold Problem |
1486B - Eastern Exhibition | 1363A - Odd Selection |
131B - Opposites Attract | 490C - Hacking Cypher |
158B - Taxi | 41C - Email address |
1373D - Maximum Sum on Even Positions | 1574C - Slay the Dragon |
621A - Wet Shark and Odd and Even | 1395A - Boboniu Likes to Color Balls |
1637C - Andrew and Stones | 1334B - Middle Class |
260C - Balls and Boxes | 1554A - Cherry |