/*
    _____
  .'     '.
 /  0   0  \
|     ^     |
|  \     /  |
 \  '---'  /
  '._____.'
*/
#include <bits/stdc++.h>
#include <ext/pb_ds/tree_policy.hpp>
#include <ext/pb_ds/assoc_container.hpp>

using namespace std;
using namespace __gnu_pbds;

struct chash
{
	int operator()(int x) const
	{
		x ^= (x >> 20) ^ (x >> 12);
		return x ^ (x >> 7) ^ (x >> 4);
	}
};

template<typename T> using ordered_set = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
template<typename T, typename U> using hashtable = gp_hash_table<T, U, chash>;
random_device(rd);
mt19937 rng(rd());

template<class T>
void readi(T &x)
{
	T input = 0;
	bool negative = false;
	char c = ' ';
	while (c < '-')
	{
		c = getchar();
	}
	if (c == '-')
	{
		negative = true;
		c = getchar();
	}
	while (c >= '0')
	{
		input = input * 10 + (c - '0');
		c = getchar();
	}
	if (negative)
	{
		input = -input;
	}
	x = input;
}
template<class T>
void printi(T output)
{
	if (output == 0)
	{
		putchar('0');
		return;
	}
	if (output < 0)
	{
		putchar('-');
		output = -output;
	}
	int aout[20];
	int ilen = 0;
	while(output)
	{
		aout[ilen] = ((output % 10));
		output /= 10;
		ilen++;
	}
	for (int i = ilen - 1; i >= 0; i--)
	{
		putchar(aout[i] + '0');
	}
	return;
}
template<class T>
void ckmin(T &a, T b)
{
	a = min(a, b);
}
template<class T>
void ckmax(T &a, T b)
{
	a = max(a, b);
}
template<class T, class U>
T nmod(T &x, U mod)
{
	if (x >= mod) x -= mod;
}
template<class T>
T gcd(T a, T b)
{
	return (b ? gcd(b, a % b) : a);
}
template<class T>
T randomize(T mod)
{
	return (uniform_int_distribution<T>(0, mod - 1))(rng);
}

#define y0 ___y0
#define y1 ___y1
#define MP make_pair
#define MT make_tuple
#define PB push_back
#define PF push_front
#define LB lower_bound
#define UB upper_bound
#define fi first
#define se second
#define debug(x) cerr << #x << " = " << x << endl;

const long double PI = 4.0 * atan(1.0);
const long double EPS = 1e-10;

#define MAGIC 347
#define SINF 10007
#define CO 1000007
#define INF 1000000007
#define BIG 1000000931
#define LARGE 1696969696967ll
#define GIANT 2564008813937411ll
#define LLINF 2696969696969696969ll
#define MAXN 100013

typedef long long ll;
typedef long double ld;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
typedef pair<ld, ld> pdd;

int N;
pll arr[MAXN];
int subtree[MAXN];
int parent[MAXN];
int ranking[MAXN];
int depth[MAXN];
ll tot;

int indexof(ll x)
{
	int w = lower_bound(arr, arr + N, MP(x, -LLINF)) - arr;
	if (w == N || arr[w].fi != x)
	{
		return -1;
	}
	return w;
}

int32_t main()
{
	ios_base::sync_with_stdio(0);
	// cout << fixed << setprecision(10);
	// cerr << fixed << setprecision(10);
	// freopen ("file.in", "r", stdin);
	// freopen ("file.out", "w", stdout);
	cin >> N;
	for (int i = 0; i < N; i++)
	{
		cin >> arr[i].fi;
		arr[i].se = i;
	}
	sort(arr, arr + N);
	for (int i = 0; i < N; i++)
	{
		ranking[arr[i].se] = i;
	}
	//u have them in increasing order of sum to root!
	for (int i = N - 1; i > 0; i--)
	{
    	//the values of D are all distinct!!!!
		subtree[i]++;
		int idx = indexof(arr[i].fi + 2 * subtree[i] - N);
		if (idx == -1 || idx >= i)
		{
			cout << "-1\n";
			return 0;
		}
		parent[i] = idx;
		subtree[idx] += subtree[i];
	}
	subtree[0]++;
	depth[0] = 0;
	for (int i = 1; i < N; i++)
	{
		depth[i] = depth[parent[i]] + 1;
	}
	for (int i = 0; i < N; i++)
	{
		tot += depth[i];
	}
	// cerr << "fuck\n";
	if (tot != arr[0].fi)
	{
		cout << "-1\n";
		return 0;
	}
	for (int i = 0; i < N; i++)
	{
		if (ranking[i] == 0) continue;
		cout << i + 1 << ' ' << arr[parent[ranking[i]]].se + 1 << '\n';
	}
	// cerr << "time elapsed = " << (clock() / (CLOCKS_PER_SEC / 1000)) << " ms" << endl;
	return 0;
}


Measured memory_bytes: 4608