/*
このコード、と～おれ!
Be accepted!
∧＿∧　
（｡･ω･｡)つ━☆・*。
⊂　　 ノ 　　　・゜+.
　しーＪ　　　°。+ *´¨)
 　　　　　　　　　.· ´¸.·*´¨) ¸.·*¨)
		  　　　　　　　　　　(¸.·´ (¸.·'* ☆
*/

#include <cstdio>
#include <algorithm>
#include <string>
#include <cmath>
#include <cstring>
#include <vector>
#include <numeric>
#include <iostream>
#include <random>
#include <map>
#include <unordered_map>
#include <queue>
#include <regex>
#include <functional>
#include <complex>
#include <list>
#include <cassert>
#include <iomanip>
#include <set>
#include <stack>
#include <bitset>
#include <array>
#include <chrono>
#include <limits>

//#pragma GCC target("arch=skylake-avx512")
//#pragma GCC target("avx2")
//#pragma GCC optimize("O3")
//#pragma GCC optimize("Ofast")
//#pragma GCC target("sse4")
//#pragma GCC optimize("unroll-loops")
//#pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,tune=native")
#define repeat(i, n, m) for(int i = n; i < (m); ++i)
#define rep(i, n) for(int i = 0; i < (n); ++i)
#define printynl(a) printf(a ? "yes\n" : "no\n")
#define printyn(a) printf(a ? "Yes\n" : "No\n")
#define printYN(a) printf(a ? "YES\n" : "NO\n")
#define printim(a) printf(a ? "possible\n" : "imposible\n")
#define printdb(a) printf("%.50lf\n", a)
#define printLdb(a) printf("%.50Lf\n", a)
#define printdbd(a) printf("%.16lf\n", a)
#define prints(s) printf("%s\n", s.c_str())
#define all(x) (x).begin(), (x).end()
#define deg_to_rad(deg) (((deg)/360.0L)*2.0L*PI)
#define rad_to_deg(rad) (((rad)/2.0L/PI)*360.0L)
#define Please return
#define AC 0
#define manhattan_dist(a, b, c, d) (abs(a - c) + abs(b - d))

using ll = long long;
using ull = unsigned long long;

constexpr int INF = 1073741823;
constexpr int MINF = -1073741823;
constexpr ll LINF = ll(4661686018427387903);
constexpr ll MOD = 1e9 + 7;
constexpr ll mod = 998244353;
constexpr long double eps = 1e-14;
const long double PI = acosl(-1.0L);

using namespace std;

void scans(string& str) {
	char c;
	str = "";
	scanf("%c", &c);
	if (c == NULL)return;
	else if (c == '\n')scanf("%c", &c);
	while (c != '\n' && c != -1 && c != ' ') {
		str += c;
		scanf("%c", &c);
	}
}

void scanc(char& str) {
	char c;
	scanf("%c", &c);
	if (c == -1)return;
	while (c == '\n') {
		scanf("%c", &c);
	}
	str = c;
}

double acot(double x) {
	return PI / 2 - atan(x);
}

ll LSB(ll n) { return (n & (-n)); }

template<typename T>
inline T chmin(T& a, const T& b) {
	if (a > b)a = b;
	return a;
}

template<typename T>
inline T chmax(T& a, const T& b) {
	if (a < b)a = b;
	return a;
}


//cpp_int
#if __has_include(<boost/multiprecision/cpp_int.hpp>)
#include <boost/multiprecision/cpp_int.hpp>
#include <boost/multiprecision/cpp_dec_float.hpp>
using namespace boost::multiprecision;
#else
using cpp_int = ll;
#endif

//atcoder library
#if __has_include(<atcoder/all>)
#include <atcoder/all>
//using namespace atcoder;
#endif

/*
	random_device seed_gen;
	mt19937 engine(seed_gen());
	uniform_int_distribution dist(1, 100);
*/


/*----------------------------------------------------------------------------------*/



int main() {

	int n;
	scanf("%d", &n);
	vector<ll> a(n);
	rep(i, n)scanf("%lld", &a[i]);
	if (n >= 4) {
		puts("0");
		vector<int> odd, even;
		rep(i, n) {
			if (a[i] % 2)odd.push_back(i + 1);
			else even.push_back(i + 1);
		}
		sort(all(odd), greater<int>());
		sort(all(even), greater<int>());
		if (even.size() > 1) {
			printf("%d %d\n", even.back(), even.front());
			rep(i, n - 2)printf("1 %d\n", n - 1 - i);
		}
		else if (even.size() == 1) {
			printf("%d %d\n%d %d\n%d %d\n", odd[0], odd[1],
				n - 1, even.back() - (even.back() > odd[1]),
				n - 2, n - 3);
			rep(i, n - 4)printf("1 %d\n", n - 3 - i);
		}
		else {
			printf("%d %d\n%d %d\n%d %d\n", odd[0], odd[1],
				odd[2], odd[3],
				n - 2, n - 3);
			rep(i, n - 4)printf("1 %d\n", n - 3 - i);
		}
	}
	else {
		if (n == 2) {
			if (gcd(a[0], a[1]) != 1) {
				puts("0\n1 2");
			}
			else {
				printf("%lld\n1 2\n", (a[0] - 1) * (a[1] - 1));
			}
		}
		else {
			if (gcd(a[0], a[1]) != 1) {
				puts("0\n1 2\n1 2");
			}
			else if (gcd(a[0], a[2]) != 1){
				puts("0\n1 3\n1 2");
			}
			else if (gcd(a[1], a[2]) != 1) {
				puts("0\n3 2\n1 2");
			}
			else {
				vector<int> perm = { 0, 1, 2 };
				ll score = LINF;
				pair<int, int> ans;
				do {
					ll xx = (a[perm[0]] - 1) * (a[perm[1]] - 1);
					if (gcd(a[perm[2]], xx) != 1) {
						score = 0;
						ans = { perm[0] + 1, perm[1] + 1 };
					}
					else if (score > (a[perm[2]] - 1) * (xx - 1)) {
						score = (a[perm[2]] - 1) * (xx - 1);
						ans = { perm[0] + 1, perm[1] + 1 };
					}
				} while (next_permutation(all(perm)));
				printf("%lld\n%d %d\n1 2", score, ans.first, ans.second);
			}
		}
	}

	Please AC;
}