#include<bits/stdc++.h>
#define ll long long
using namespace std;
ll gcd(ll x,ll y){
	if(y==0)return x;
	return gcd(y,x%y);
}
signed main(){
	int T;
	scanf("%d",&T);
	while(T--){
		ll n,k;
		scanf("%lld%lld",&n,&k);
		if(n<k){
			printf("-1\n");
			continue;
		}
		if(gcd(n,n-k)==1||n-k>k)printf("%lld %lld\n",k,n-k);
		else printf("-1\n");
	}
	return 0;
}

rt,sub3全过了，sub1,sub2各WA一个