#include <bits/stdc++.h>
using namespace std;

struct iofast_t {
    iofast_t() {
        ios::sync_with_stdio(false);
        cin.tie(nullptr);
    }
} iofast;

struct uns_t {} uns;
template <typename Element, typename Head, typename ...Args>
auto vec(Element init, Head arg, Args ...args) {
    if constexpr (sizeof...(Args) == 0) return vector(arg, init);
    else return vector(arg, vec(init, args...));
}
template <typename Element, typename Head, typename ...Args>
auto vec(uns_t, Head arg, Args ...args) {
    return vec(Element(), arg, args...);
}

template <typename Container>
auto distance(const Container &c, decltype(begin(c)) iter) {
    return distance(begin(c), iter);
}

template <typename RIter, typename Compare = less<typename iterator_traits<RIter>::value_type>>
auto isort(RIter first, RIter last, Compare comp = Compare()) {
    vector<int> i(distance(first, last));
    iota(begin(i), end(i), 0);
    sort(begin(i), end(i), [&](auto x, auto y) {
        return comp(*(first + x), *(first + y));
    });
    return i;
}

template <typename, template <typename> typename, typename = void_t<>>
struct detect : false_type {};
template <typename T, template <typename> typename Check>
struct detect<T, Check, void_t<Check<T>>> : true_type {};
template <typename T, template <typename> typename Check>
constexpr inline bool detect_v = detect<T, Check>::value;

template <typename T>
using has_member_sort = decltype(declval<T>().sort());

template <typename Container, typename Compare = less<typename Container::value_type>>
auto sorted(Container c, Compare comp = Compare()) {
    if constexpr (detect_v<Container, has_member_sort>) {
        c.sort(comp);
        return c;
    }
    else {
        sort(begin(c), end(c), comp);
        return c;
    }
}

template <typename Container, typename Compare = equal_to<typename Container::value_type>>
auto uniqued(Container c, Compare comp = Compare()) {
    c.erase(unique(begin(c), end(c), comp), end(c));
    return c;
}

template <typename T, typename Compare = less<T>>
T &chmin(T &l, T r, Compare &&f = less<T>()) { return l = min(l, r, f); }
template <typename T, typename Compare = less<T>>
T &chmax(T &l, T r, Compare &&f = less<T>()) { return l = max(l, r, f); }

template <typename F>
constexpr auto fix(F &&f) noexcept {
    return [f = std::tuple<F>(std::forward<F>(f))](auto &&...args) mutable {
        return std::get<0>(f)(fix(std::get<0>(f)), std::forward<decltype(args)>(args)...);
    };
}

int main() {
    constexpr auto inf = INT64_MAX / 4;

    int n; cin >> n;
    auto a = vec<int64_t>(uns, n);
    for (auto &e : a) cin >> e;

    if (4 <= n) {
        cout << 0 << endl;

        cout << 1 << " " << 2 << endl;
        cout << 1 << " " << 2 << endl;
        for (int i = 2; i < n - 1; ++i) {
            cout << n - i << " " << n - i - 1 << endl;
        }

        return 0;
    }

    auto f = [](int64_t x, int64_t y) -> int64_t {
        if (x == 0 || y == 0 || gcd(x, y) != 1) {
            return 0;
        }
        return (x - 1) * (y - 1);
    };

    auto p = vec<tuple<int, int>>(uns, 0);
    for (int i = 0; i < n; ++i) {
        for (int j = i + 1; j < n; ++j) {
            p.push_back({ i, j });
        }
    }

    tuple<int64_t, vector<tuple<int, int>>> ans = { inf, {} };

    auto w = vec<tuple<int, int>>(uns, 0);

    fix([&](auto g, int d = 0) -> void {
        if (n - 1 <= d) {
            auto b = a;
            auto s = vec<tuple<int, int>>(uns, 0);

            for (auto [i, j] : w) {
                if (size(b) <= j) {
                    return;
                }
                b.push_back(f(b[i], b[j]));
                s.push_back({ i, j });

                b.erase(begin(b) + j);
                b.erase(begin(b) + i);
            }

            chmin(ans, make_tuple(b[0], s));
            return;
        }

        for (auto [i, j] : p) {
            w.push_back({ i, j });
            g(d + 1);
            w.pop_back();
        }
    })();

    cout << get<0>(ans) << endl;
    for (auto [i, j] : get<1>(ans)) {
        cout << i + 1 << " " << j + 1 << endl;
    }
}