#include <algorithm>
#include <atcoder/all>
#include <bitset>
#include <cassert>
#include <cmath>
#include <ctime>
#include <functional>
#include <iomanip>
#include <iostream>
#include <map>
#include <queue>
#include <random>
#include <set>
#include <stack>
#include <string>
#include <tuple>
#include <unordered_map>
#include <unordered_set>
#include <utility>
#include <vector>
using namespace std;
using namespace atcoder;
typedef long long ll;
#define rep(i, n) for (int i = 0; i < (int)(n); i++)
#define repr(i, n) for (int i = (int)(n) - 1; i >= 0; i--)
#define repk(i, k, n) for (int i = k; i < (int)(n); i++)
#define all(v) v.begin(), v.end()
#define mod1 1000000007
#define mod2 998244353
#define mod3 100000007
#define vi vector<int>
#define vs vector<string>
#define vc vector<char>
#define vl vector<ll>
#define vb vector<bool>
#define vvi vector<vector<int>>
#define vvc vector<vector<char>>
#define vvl vector<vector<ll>>
#define vvb vector<vector<bool>>
#define vvvi vector<vector<vector<int>>>
#define vvvl vector<vector<vector<ll>>>
#define pii pair<int, int>
#define pil pair<int, ll>
#define pli pair<ll, int>
#define pll pair<ll, ll>
#define vpii vector<pair<int, int>>
#define vpll vector<pair<ll, ll>>
#define vvpii vector<vector<pair<int, int>>>
#define vvpll vector<vector<pair<ll, ll>>>

template <typename T>
void debug(T e) {
    cerr << e << endl;
}

template <typename T>
void debug(vector<T> &v) {
    rep(i, v.size()) { cerr << v[i] << " "; }
    cerr << endl;
}

template <typename T>
void debug(vector<vector<T>> &v) {
    rep(i, v.size()) {
        rep(j, v[i].size()) { cerr << v[i][j] << " "; }
        cerr << endl;
    }
}

template <typename T>
void debug(vector<pair<T, T>> &v) {
    rep(i, v.size()) { cerr << v[i].first << " " << v[i].second << endl; }
}

template <typename T>
void debug(set<T> &st) {
    for (auto itr = st.begin(); itr != st.end(); itr++) {
        cerr << *itr << " ";
    }
    cerr << endl;
}

template <typename T>
void debug(multiset<T> &ms) {
    for (auto itr = ms.begin(); itr != ms.end(); itr++) {
        cerr << *itr << " ";
    }
    cerr << endl;
}

template <typename T>
void debug(map<T, T> &mp) {
    for (auto itr = mp.begin(); itr != mp.end(); itr++) {
        cerr << itr->first << " " << itr->second << endl;
    }
}

void debug_out() { cerr << endl; }

template <typename Head, typename... Tail>
void debug_out(Head H, Tail... T) {
    cerr << H << " ";
    debug_out(T...);
}

using mint = modint998244353;

void debug_mint1(vector<mint> &vec) {
    for (int i = 0; i < vec.size(); i++) {
        cerr << vec[i].val() << " ";
    }
    cerr << endl;
}

void debug_mint2(vector<vector<mint>> &vec) {
    for (int i = 0; i < vec.size(); i++) {
        for (int j = 0; j < vec[i].size(); j++) {
            cerr << vec[i][j].val() << " ";
        }
        cerr << endl;
    }
}

ll my_gcd(ll a, ll b) {
    ll ret = 0;
    if (a < b) {
        swap(a, b);
    }
    if (b == 0) {
        ret = a;
    } else {
        ret = my_gcd(b, a % b);
    }
    return ret;
}

ll f(ll x, ll y){
    ll g = my_gcd(x, y);
    if (g == 1){
        return (x - 1) * (y - 1);
    }
    return 0LL;
}

int main() {
    ll N;
    cin >> N;
    vector<ll> A(N);
    for (ll i = 0; i < N; i++){
        cin >> A[i];
    }
    if (N == 2){
        cout << f(A[0], A[1]) << endl;
        cout << 1 << " " << 2 << endl;
        return 0;
    }
    else if (N == 3){
        ll v12 = f(f(A[0], A[1]), A[2]);
        ll v13 = f(f(A[0], A[2]), A[1]);
        ll v23 = f(f(A[1], A[2]), A[0]);
        if (v12 <= v13 && v12 <= v23){
            cout << v12 << endl;
            cout << 1 << " " << 2 << endl;
            cout << 1 << " " << 2 << endl;
        }
        else if (v13 <= v12 && v13 <= v23){
            cout << v13 << endl;
            cout << 1 << " " << 3 << endl;
            cout << 1 << " " << 2 << endl;
        }
        else{
            cout << v23 << endl;
            cout << 2 << " " << 3 << endl;
            cout << 1 << " " << 2 << endl;
        }
        return 0;
    }
    // 偶数が 2 個以上ある場合はそれを選べば 0 が作れるので、初手はそうする
    ll e1 = -1;
    ll e2 = -1;
    for (ll i = 0; i < N; i++){
        if (A[i] % 2 == 0){
            if (e1 == -1) e1 = i;
            else e2 = i;
        }
    }
    if (e2 != -1){
        cout << 0 << endl;
        cout << e1 + 1 << " " << e2 + 1 << endl;
        for (ll i = 0; i < N - 2; i++){
            cout << 1 << " " << N - 1 - i << endl;
        }
    }
    else if (e1 != -1){
        // 偶数が 1 個のときは、奇数 2 個を先に組み合わせてからそれと偶数をマッチさせるとうまくいく
        if (e1 <= 1){
            cout << 0 << endl;
            cout << 3 << " " << 4 << endl;
            cout << e1 + 1 << " " << N - 1 << endl;
            for (ll i = 0; i < N - 3; i++){
                cout << 1 << " " << N - 2 - i << endl;
            }
        }
        else{
            cout << 0 << endl;
            cout << 1 << " " << 2 << endl;
            cout << e1 - 1 << " " << N - 1 << endl;
            for (ll i = 0; i < N - 3; i++){
                cout << 1 << " " << N - 2 - i << endl;
            }
        }
    }
    else{
        // そうでない場合は奇数 2 個同士でマッチング
        cout << 0 << endl;
        cout << 1 << " " << 2 << endl;
        cout << 1 << " " << 2 << endl;
        for (ll i = 0; i < N - 3; i++){
            cout << 1 << " " << N - 2 - i << endl;
        }
    }
}