#include <bits/stdc++.h>
#pragma GCC diagnostic ignored "-Wsign-compare"
#pragma GCC diagnostic ignored "-Wsign-conversion"
#define NDEBUG
#define SHOW(...) static_cast<void>(0)
//!===========================================================!//
//!  dP     dP                          dP                    !//
//!  88     88                          88                    !//
//!  88aaaaa88a .d8888b. .d8888b. .d888b88 .d8888b. 88d888b.  !//
//!  88     88  88ooood8 88'  '88 88'  '88 88ooood8 88'  '88  !//
//!  88     88  88.  ... 88.  .88 88.  .88 88.  ... 88        !//
//!  dP     dP  '88888P' '88888P8 '88888P8 '88888P' dP        !//
//!===========================================================!//
template <typename T>
T read()
{
    T v;
    return std::cin >> v, v;
}
template <typename T>
std::vector<T> readVec(const std::size_t l)
{
    std::vector<T> v(l);
    for (auto& e : v) { std::cin >> e; }
    return v;
}
using ld = long double;
using uint = unsigned int;
using ll = long long;
using ull = unsigned long long;
constexpr unsigned int MOD = 1000000007;
template <typename T>
constexpr T INF = std::numeric_limits<T>::max() / 4;
template <typename F>
constexpr F PI = static_cast<F>(3.1415926535897932385);
std::mt19937 mt{std::random_device{}()};
template <typename T>
bool chmin(T& a, const T& b) { return (a > b ? a = b, true : false); }
template <typename T>
bool chmax(T& a, const T& b) { return (a < b ? a = b, true : false); }
template <typename T>
std::vector<T> Vec(const std::size_t n, T v) { return std::vector<T>(n, v); }
template <class... Args>
auto Vec(const std::size_t n, Args... args) { return std::vector<decltype(Vec(args...))>(n, Vec(args...)); }
template <typename T>
constexpr T popCount(const T u)
{
#ifdef __has_builtin
    return u == 0 ? T(0) : (T)__builtin_popcountll(u);
#else
    unsigned long long v = static_cast<unsigned long long>(u);
    return v = (v & 0x5555555555555555ULL) + (v >> 1 & 0x5555555555555555ULL), v = (v & 0x3333333333333333ULL) + (v >> 2 & 0x3333333333333333ULL), v = (v + (v >> 4)) & 0x0F0F0F0F0F0F0F0FULL, static_cast<T>(v * 0x0101010101010101ULL >> 56 & 0x7f);
#endif
}
template <typename T>
constexpr T log2p1(const T u)
{
#ifdef __has_builtin
    return u == 0 ? T(0) : T(64 - __builtin_clzll(u));
#else
    unsigned long long v = static_cast<unsigned long long>(u);
    return v = static_cast<unsigned long long>(v), v |= (v >> 1), v |= (v >> 2), v |= (v >> 4), v |= (v >> 8), v |= (v >> 16), v |= (v >> 32), popCount(v);
#endif
}
template <typename T>
constexpr T clog(const T v) { return v == 0 ? T(0) : log2p1(v - 1); }
template <typename T>
constexpr T msbp1(const T v) { return log2p1(v); }
template <typename T>
constexpr T lsbp1(const T v)
{
#ifdef __has_builtin
    return __builtin_ffsll(v);
#else
    return v == 0 ? T(0) : popCount((v & (-v)) - T(1)) + T(1);
#endif
}
template <typename T>
constexpr bool ispow2(const T v) { return popCount(v) == 1; }
template <typename T>
constexpr T ceil2(const T v) { return v == 0 ? T(1) : T(1) << log2p1(v - 1); }
template <typename T>
constexpr T floor2(const T v) { return v == 0 ? T(0) : T(1) << (log2p1(v) - 1); }
//!=================================================!//
//!   .88888.                             dP        !//
//!  d8'   '88                            88        !//
//!  88        88d888b. .d8888b. 88d888b. 88d888b.  !//
//!  88   YP88 88'  '88 88'  '88 88'  '88 88'  '88  !//
//!  Y8.   .88 88       88.  .88 88.  .88 88    88  !//
//!   '88888'  dP       '88888P8 88Y888P' dP    dP  !//
//!                              88                 !//
//!                              dP                 !//
//!=================================================!//
template <typename Cost>
struct BaseGraph
{
    BaseGraph(const std::size_t v) : V{v}, edge(v), rev_edge(v) {}
    void addEdge(const std::size_t from, const std::size_t to, const Cost cost, const bool bi = false)
    {
        assert(from < V), assert(to < V);
        edge[from].push_back(Edge{to, cost}), rev_edge[to].push_back(Edge(from, cost));
        if (bi) { addEdge(to, from, cost, false); }
    }
    struct Edge
    {
        Edge(const std::size_t to, const Cost cost) : to{to}, cost{cost} {}
        const std::size_t to;
        const Cost cost;
        bool operator<(const Edge& e) const { return cost != e.cost ? cost < e.cost : to < e.to; }
    };
    const std::vector<Edge>& operator[](const std::size_t i) const { return assert(i < V), edge[i]; }
    friend std::ostream& operator<<(std::ostream& os, const BaseGraph& g)
    {
        os << "[\n";
        for (std::size_t i = 0; i < g.V; i++) {
            for (const auto& e : g.edge[i]) { os << i << "->" << e.to << ":" << e.cost << "\n"; }
        }
        return (os << "]\n");
    }
    static std::size_t to(const Edge& e) { return e.to; }
    const std::size_t V;
    std::vector<std::vector<Edge>> edge, rev_edge;
};
template <>
struct BaseGraph<void>
{
    BaseGraph(const std::size_t v) : V{v}, edge(v), rev_edge(v) {}
    void addEdge(const std::size_t from, const std::size_t to, const bool bi = false)
    {
        assert(from < V), assert(to < V);
        edge[from].push_back(to), rev_edge[to].push_back(from);
        if (bi) { addEdge(to, from, false); }
    }
    const std::vector<std::size_t>& operator[](const std::size_t i) const { return assert(i < V), edge[i]; }
    friend std::ostream& operator<<(std::ostream& os, const BaseGraph& g)
    {
        os << "[\n";
        for (std::size_t i = 0; i < g.V; i++) {
            for (const std::size_t to : g.edge[i]) { os << i << "->" << to << "\n"; }
        }
        return (os << "]\n");
    }
    static std::size_t to(const std::size_t e) { return e; }
    const std::size_t V;
    std::vector<std::vector<std::size_t>> edge, rev_edge;
};
using Graph = BaseGraph<void>;
using Tree = Graph;
template <typename Cost>
using CostGraph = BaseGraph<Cost>;
template <typename Cost>
using CostTree = CostGraph<Cost>;
//!==============================================================================!//
//!  dP     dP          oo                       88888888b oo                dP  !//
//!  88     88                                   88                          88  !//
//!  88     88 88d888b. dP .d8888b. 88d888b.    a88aaaa    dP 88d888b. .d888b88  !//
//!  88     88 88'  '88 88 88'  '88 88'  '88     88        88 88'  '88 88'  '88  !//
//!  Y8.   .8P 88    88 88 88.  .88 88    88     88        88 88    88 88.  .88  !//
//!  'Y88888P' dP    dP dP '88888P' dP    dP     dP        dP dP    dP '88888P8  !//
//!==============================================================================!//
class UnionFind
{
public:
    UnionFind(const std::size_t v) : V(v), parent(v), size(v, 1) { std::iota(parent.begin(), parent.end(), 0); }
    std::size_t find(const std::size_t a) { return assert(a < V), parent[a] == a ? a : parent[a] = find(parent[a]); }
    bool same(const std::size_t a, const std::size_t b)
    {
        assert(a < V), assert(b < V);
        return find(a) == find(b);
    }
    void unite(std::size_t a, std::size_t b)
    {
        assert(a < V), assert(b < V);
        a = find(a), b = find(b);
        if (a == b) { return; }
        if (size[a] < size[b]) { std::swap(a, b); }
        size[a] += size[b], parent[b] = a;
    }
    std::size_t getSize(const std::size_t a) { return assert(a < V), size[find(a)]; }
    friend std::ostream& operator<<(std::ostream& os, const UnionFind& uf)
    {
        os << "[";
        for (std::size_t i = 0; i < uf.parent.size(); i++) { os << uf.parent[i] << (i + 1 == uf.parent.size() ? "" : ","); }
        return (os << "]\n");
    }

private:
    const std::size_t V;
    std::vector<std::size_t> parent, size;
};
//!=====================================!//
//!  8888ba.88ba           oo           !//
//!  88  '8b  '8b                       !//
//!  88   88   88 .d8888b. dP 88d888b.  !//
//!  88   88   88 88'  '88 88 88'  '88  !//
//!  88   88   88 88.  .88 88 88    88  !//
//!  dP   dP   dP '88888P8 dP dP    dP  !//
//!=====================================!//
int main()
{
    const int N = read<int>();
    const auto D = readVec<ll>(N);
    std::map<ll, int, std::greater<ll>> mp;
    for (int i = 0; i < N; i++) { mp[D[i]] = i; }
    UnionFind uf(N);
    Tree T(N);
    for (const auto& p : mp) {
        const ll d = p.first;
        const int v = p.second;
        const ll dpar = (d - N + 2 * uf.getSize(v));
        if (uf.getSize(v) == N) { break; }
        if (mp.find(dpar) == mp.end()) { return std::cout << -1 << std::endl, 0; }
        const int par = mp[dpar];
        T.addEdge(par, v, true), uf.unite(par, v);
    }
    ll ans = 0;
    auto dfs = [&](auto&& self, const int s, const int p, const ll d) -> void {
        ans += d;
        for (const int to : T[s]) {
            if (to == p) { continue; }
            self(self, to, s, d + 1);
        }
    };
    dfs(dfs, 0, -1, 0);
    if (ans != D[0]) { return std::cout << -1 << std::endl, 0; }
    for (int i = 0; i < N; i++) {
        for (const int to : T[i]) {
            if (to > i) { std::cout << i + 1 << " " << to + 1 << std::endl; }
        }
    }
    return 0;
}


Measured memory_bytes: 24192