#include <bits/stdc++.h>
using namespace std;
#define int long long
const int maxn=1e6+10;
bool vis[maxn];
int p[maxn],len;
void xx()
{
    int n=sqrt(1e10+10);
    for(int i=2;i<=n;i++)
    {
        if(vis[i]==0)
        {
            p[++len]=i;
        }
        for(int j=1;p[j]<=n/i;j++)
        {
            vis[i*p[j]]=1;
            if(i%p[j]==0)
                break;
        }
    }
}
signed main() 
{
    xx();
    int t;
    cin>>t;
    while(t--)
    {
        int n,m;
        cin>>n>>m;
        if(n<m) swap(m,n);
        int y=n-m;
        int x=y;
        if(y==0) 
        {
            if(m==1&&n==1)
            {
                cout<<-1<<" "<<-1<<endl;
                continue;
            }
            y=n;
            x=2;
            cout<<x<<" "<<y<<endl;
            continue;
        }
        if(y==1)
        {
            cout<<-1<<" "<<-1<<endl;
            continue;
        }
        for(int i=1;i<=len;i++)
        {
            if(y%p[i]==0)
            {
                x=p[i];
                break;
            }
        }
        cout<<x<<" "<<y<<endl;
    }
    return 0;
}