B_Equalise_by_Divide.cpp

#include <bits/stdc++.h>
using namespace std;
 
typedef long long ll;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
typedef pair<string, string> pss;
typedef vector<int> vi;
typedef vector<vi> vvi;
typedef vector<pii> vii;
typedef vector<ll> vl;
typedef vector<vl> vvl;
#define FOR(a, b, c) for (int(a) = (b); (a) < (c); ++(a))
#define FORN(a, b, c) for (int(a) = (b); (a) <= (c); ++(a))
#define FORD(a, b, c) for (int(a) = (b); (a) >= (c); --(a))
#define FORSQ(a, b, c) for (int(a) = (b); (a) * (a) <= (c); ++(a))
#define FORC(a, b, c) for (char(a) = (b); (a) <= (c); ++(a))
#define FOREACH(a, b) for (auto&(a) : (b))
#define MAX(a, b) a = max(a, b)
#define MIN(a, b) a = min(a, b)
#define YES                          cout << "YES\n";
#define NO                           cout << "NO\n";
#define Yes                          cout << "Yes\n";
#define No                           cout << "No\n";
#define TC(t) while (t--)
#define mod 1000000007
#define FastIO ios_base::sync_with_stdio(false); cin.tie(NULL); cout.tie(NULL);
ll inv(ll i) {if (i == 1) return 1; return (mod - ((mod / i) * inv(mod % i)) % mod) % mod;}
 
ll mod_mul(ll a, ll b) {a = a % mod; b = b % mod; return (((a * b) % mod) + mod) % mod;}
 
ll mod_add(ll a, ll b) {a = a % mod; b = b % mod; return (((a + b) % mod) + mod) % mod;}
 
ll gcd(ll a, ll b) { if (b == 0) return a; return gcd(b, a % b);}
 
ll ceil_div(ll a, ll b) {return a % b == 0 ? a / b : a / b + 1;}

class dsu {

public:
	vector<int> parent;
	dsu(int n) {
		parent.resize(n);
		for (int i = 0; i < n; i++) parent[i] = i;

	}


	int findParent(int u) {
		return parent[u] = (parent[u] == u ? u : findParent(parent[u]));
	}

	void _union(int u, int v) {
		int pv = findParent(v);
		int pu = findParent(u);

		if (pv != pu) parent[pv] = pu;
	}
};
 
ll pwr(ll a, ll b) {a %= mod; ll res = 1; while (b > 0) {if (b & 1) res = res * a % mod; a = a * a % mod; b >>= 1;} return res;}
bool primes[1000001]={true};
int N=1000000;
void sieve(){
   FOR(i,0,N){
    if(primes[i]==true){
        for(int j=i*i;j<=N;j+=i)primes[i]=false;
    }
   }
}


bool chk(vector<ll> a) {
    for(ll i = 0; i < a.size() - 1; i++) if(a[i] != a[i+1]) return false;
    return true;
}

void solve() {
    ll n; cin >> n;
    vector<ll> a(n);
    for(ll i = 0; i < n; i++) cin >> a[i];
    
    if(chk(a)) {
        cout << 0 << endl;
        return;
    }
    vector<vector<ll>> ans;
    vector<ll> prev = a;
    while(chk(a) == false) {
        ll mini = INT_MAX;
        ll ind = -1;
        for(ll i = 0; i < n; i++) {
            if(a[i] < mini) {
                mini = a[i];
                ind = i;
            }
        }
        bool ok = false;
        for(ll i = 0; i < n; i++) {
            if(a[i] != mini and a[i] > mini) {
                ll y = (a[i] / mini);
                if(a[i] % mini != 0) {
                    y++;
                }
                ans.push_back({i , ind});
                a[i] = y;
                ok = true;
            }
        }
        if(a == prev) {
            cout << -1 << endl;
            return;
        }
        prev = a;
    }
    cout << ans.size() << endl;
    for(auto it : ans) cout << it[0] + 1 << " " << it[1] + 1 << endl;
    
}

int32_t main(){
    ios_base::sync_with_stdio(false);
cin.tie(0);
cout.tie(0);
  ll t=1;
  cin>>t;
  TC(t){
    solve();
  }
}