#include <bits/stdc++.h>
using namespace std;
 
#pragma region Macros
#define Faster ios_base::sync_with_stdio(false); cin.tie(0); cout.tie(0);
#define ll long long
#define ld long double
#define pii pair<int, int>
#define pll pair<long long, long long>
#define all(x) x.begin(), x.end()
#define rall(x) x.rbegin(), x.rend()
#define pb push_back
#define ff first
#define ss second
#define endl '\n'
#define yes cout << "YES" << endl
#define no cout << "NO" << endl
#define m1 cout << -1 << endl
#pragma endregion
 
#pragma region Math
const ll MOD = 1e9 + 7;
ll gcd(ll a, ll b) { return __gcd(a, b); }
ll lcm(ll a, ll b) { return (a / gcd(a, b)) * b; }
#pragma endregion
 
void solve() {
    int a,b;    cin>>a>>b;
    if(a<b) cout<<-1<<endl;
    else{
        cout<<2<<endl;
        cout<<a<<" "<<b<<endl;
    }
}
 
int main() {
    Faster;
    int t = 1;
    cin >> t;
    while (t--) solve();
    return 0;
}

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9 6
13 13
292 929
405 400
998 244
244 353