#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)...);
    };
}

/*

int64_t sign(int64_t x) {
    return clamp<int64_t>(x, -1, 1);
}

int64_t floor(int64_t x, int64_t y) {
    if (0 < sign(x) * sign(y)) {
        return x / y;
    }
    return -((abs(x) + abs(y) - 1) / abs(y));
}

int64_t ceil(int64_t x, int64_t y) {
    if (0 < sign(x) * sign(y)) {
        return (abs(x) + abs(y) - 1) / abs(y);
    }
    return x / y;
}

auto exgcd(int a, int b) -> tuple<int, int> {
    if (b != 0) {
        auto [xp, yp] = exgcd(b, a % b);
        return { yp, xp - (a / b) * yp };
    }

    if (0 <= a) {
        return { 1, 0 };
    }
    return { -1, 0 };
}

int f(int x, int y) {
    if (x == 0 || y == 0 || gcd(x, y) != 1) {
        return 0;
    }

    auto [xp, yp] = exgcd(x, y);

    auto check = [&](int c) {
        return 0 <= floor(yp * c, x) - ceil(-xp * c, y);
    };

    int k = x * y;
    while (0 < k && check(k - 1)) {
        --k;
    }

    return k;
}

int main() {
    for (int i = 1; i <= 100; ++i) {
        for (int j = 1; j <= 100; ++j) {
            if (gcd(i, j) == 1) {
                if ((i - 1) * (j - 1) != f(i, j)) {
                    cout << "ng" << endl;
                }
            }
        }
    }
}

*/

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

// f(x, y) の挙動から、1 回でも 0 を作ることができれば答えは 0 になる
// 偶数が 2 つ以上存在すれば 0 を作れる
// 奇数が 2 つ以上存在すれば、結果として偶数を作れるため、0 を作れる

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

    if (count(begin(a), end(a), 0) != 0) {
        int iter1 = 0;
        while (a[iter1] != 0) {
            ++iter1;
        }

        int iter2 = n - 1;
        while (iter1 == iter2) {
            --iter2;
        }

        cout << 0 << endl;

        cout << iter1 + 1 << " " << iter2 + 1 << endl;
        for (int i = 1; i < n - 1; ++i) {
            cout << (n - i) << " " << (n - i - 1) << endl;
        }

        return 0;
    }

    int even = 0;
    for (auto v : a) {
        even += (v % 2 == 0);
    }

    if (2 <= even) {
        int iter1 = 0;
        while (a[iter1] % 2 != 0) {
            ++iter1;
        }

        int iter2 = n - 1;
        while (a[iter2] % 2 != 0) {
            --iter2;
        }

        cout << 0 << endl;

        cout << iter1 + 1 << " " << iter2 + 1 << endl;
        for (int i = 1; i < n - 1; ++i) {
            cout << (n - i) << " " << (n - i - 1) << endl;
        }

        return 0;
    }

    if (n == 2) {
        cout << f(a[0], a[1]) << endl;
        cout << 1 << " " << 2 << endl;
        return 0;
    }

    if (1 <= even) {
        int iter1 = 0;
        while (a[iter1] % 2 != 0) {
            ++iter1;
        }

        int iter2 = 0;
        while (iter1 == iter2) {
            ++iter2;
        }

        cout << 0 << endl;
        cout << iter1 + 1 << " " << iter2 + 1 << endl;
        for (int i = 1; i < n - 1; ++i) {
            cout << (n - i) << " " << (n - i - 1) << endl;
        }

        return 0;
    }

    int odd = 0;
    for (auto v : a) {
        even += (v % 2 == 1);
    }

    if (n == 3 && odd == 3) {
        cout << a[0] * a[1] * a[2] << endl;
        cout << 1 << " " << 2 << endl;
        for (int i = 1; i < n - 1; ++i) {
            cout << (n - i) << " " << (n - i - 1) << endl;
        }
        return 0;
    }

    cout << 0 << endl;
    cout << 1 << " " << 2 << endl;
    for (int i = 1; i < n - 1; ++i) {
        cout << (n - i) << " " << (n - i - 1) << endl;
    }
}