#pragma GCC target("avx2")
#pragma GCC optimize("O3")
#pragma GCC optimize("unroll-loops")

#include <bits/stdc++.h>
#include <atcoder/all>

using namespace std;
using namespace atcoder;

#define overload4(_1, _2, _3, _4, name, ...) name
#define rep1(n) for(int i = 0; i < (int)(n); ++i)
#define rep2(i, n) for(int i = 0; i < (int)(n); ++i)
#define rep3(i, a, b) for(int i = (a); i < (int)(b); ++i)
#define rep4(i, a, b, c) for(int i = (a); i < (int)(b); i += (c))
#define rep(...) overload4(__VA_ARGS__, rep4, rep3, rep2, rep1)(__VA_ARGS__)

#define rrep(i,n) for(int i = (int)(n) - 1; i >= 0; --i)
#define ALL(a) a.begin(), a.end()
#define Sort(a) sort(a.begin(), a.end())
#define RSort(a) sort(a.rbegin(), a.rend())

typedef long long int ll;
typedef unsigned long long ul;
typedef long double ld;
typedef vector<int> vi;
typedef vector<long long> vll;
typedef vector<char> vc;
typedef vector<string> vst;
typedef vector<double> vd;
typedef vector<long double> vld;
typedef pair<long long, long long> P;

template<class T> long long sum(const T& a){ return accumulate(a.begin(), a.end(), 0LL); }
template<class T> auto min(const T& a){ return *min_element(a.begin(), a.end()); }
template<class T> auto max(const T& a){ return *max_element(a.begin(), a.end()); }

const long long MINF = 0x7fffffffffff;
const long long INF = 0x1fffffffffffffff;
const long long MOD = 998244353;
const long double EPS = 1e-9;
const long double PI = acos(-1);
 
template<class T> inline bool chmax(T& a, T b) { if (a < b) { a = b; return 1; } return 0; }
template<class T> inline bool chmin(T& a, T b) { if (a > b) { a = b; return 1; } return 0; }

template<typename T1, typename T2> istream &operator>>(istream &is, pair<T1, T2> &p){ is >> p.first >> p.second; return is; }
template<typename T1, typename T2> ostream &operator<<(ostream &os, const pair<T1, T2> &p){ os << "(" << p.first << ", " << p.second << ")"; return os; }
template<typename T> istream &operator>>(istream &is, vector<T> &v){ for(T &in : v) is >> in; return is; }
template<typename T> ostream &operator<<(ostream &os, const vector<T> &v){ for(int i = 0; i < (int) v.size(); ++i){ os << v[i] << (i + 1 != (int) v.size() ? " " : ""); } return os; }
template <typename T, typename S> ostream &operator<<(ostream &os, const map<T, S> &mp){ for(auto &[key, val] : mp){ os << key << ":" << val << " "; } return os; }
template <typename T> ostream &operator<<(ostream &os, const set<T> &st){ auto itr = st.begin(); for(int i = 0; i < (int)st.size(); ++i){ os << *itr << (i + 1 != (int)st.size() ? " " : ""); itr++; } return os; }
template <typename T> ostream &operator<<(ostream &os, const multiset<T> &st){ auto itr = st.begin(); for(int i = 0; i < (int)st.size(); ++i){ os << *itr << (i + 1 != (int)st.size() ? " " : ""); itr++; } return os; }
template <typename T> ostream &operator<<(ostream &os, queue<T> q){ while(q.size()){ os << q.front() << " "; q.pop(); } return os; }
template <typename T> ostream &operator<<(ostream &os, deque<T> q){ while(q.size()){ os << q.front() << " "; q.pop_front(); } return os; }
template <typename T> ostream &operator<<(ostream &os, stack<T> st){ while(st.size()){ os << st.top() << " "; st.pop(); } return os; }
template <class T, class Container, class Compare> ostream &operator<<(ostream &os, priority_queue<T, Container, Compare> pq){ while(pq.size()){ os << pq.top() << " "; pq.pop(); } return os; }

template<class T, class U> inline T vin(T& vec, U n) { vec.resize(n); for(int i = 0; i < (int) n; ++i) cin >> vec[i]; return vec; }
template<class T> inline void vout(T vec, string s = "\n"){ for(auto x : vec) cout << x << s; }
template<class... T> void in(T&... a){ (cin >> ... >> a); }
void out(){ cout << '\n'; }
template<class T, class... Ts> void out(const T& a, const Ts&... b){ cout << a; (cout << ... << (cout << ' ', b)); cout << '\n'; }
template<class T, class U> void inGraph(vector<vector<T>>& G, U n, U m, bool directed = false){ G.resize(n); for(int i = 0; i < m; ++i){ int a, b; cin >> a >> b; a--, b--; G[a].push_back(b); if(!directed) G[b].push_back(a); } }

template <typename X>
struct SegTree{
    using FX = function<X(X, X)>; // X•X -> X となる関数の型
    int n;
    FX fx;
    const X ex;
    vector<X> dat;

    SegTree(int n_, const FX &fx_, const X &ex_) : n(), fx(fx_), ex(ex_){
        int x = 1;
        while(n_ > x){
            x *= 2;
        }
        n = x;
        dat.assign(n * 2, ex);
    }

    X get(int i) const {
        return dat[i + n];
    }
    
    void set(int i, X x){ dat[i + n] = x; }

    void build(){
        for(int k = n - 1; k >= 1; k--) dat[k] = fx(dat[k * 2], dat[k * 2 + 1]);
    }

    void update(int i, X x){
        i += n;
        dat[i] = x;
        while(i > 0){
            i >>= 1;  // parent
            dat[i] = fx(dat[i * 2], dat[i * 2 + 1]);
        }
    }

    X query(int a, int b){
        X vl = ex;
        X vr = ex;
        int l = a + n;
        int r = b + n;
        while(l < r){
            if(l & 1) vl = fx(vl, dat[l++]);
            if(r & 1) vr = fx(dat[--r], vr);
            l >>= 1;
            r >>= 1;
        }
        return fx(vl, vr);
    }
    
    X operator [](int i) const {
        return dat[i + n];
    }
};

ll n;
vll a;

void input(){
    in(n);
    vin(a, n);
}

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

void solve(){
    if(n >= 4){
        vector<vll> m(2);
        rep(i, n){
            m[a[i] % 2].push_back(i);
        }
        auto fx = [](ll a, ll b){
            return a + b;
        };
        SegTree<ll> seg(2 * n, fx, 0);
        rep(i, n) seg.update(i, 1);
        auto idx = [&](ll i){
            return seg.query(0, i);
        };

        ll now = -1;
        vector<P> ans;
        auto ope = [&](ll x, ll y){
            ans.emplace_back(idx(x), idx(y));
            seg.update(x, 0);
            seg.update(y, 0);
            now++;
            seg.update(n + now, 1);
        };

        while(m[0].size() < 2){
            ll x = m[1].back();
            m[1].pop_back();
            ll y = m[1].back();
            m[1].pop_back();

            ope(x, y);
            m[0].push_back(n + now);
        }

        {
            ll x = m[0].back();
            m[0].pop_back();
            ll y = m[0].back();
            m[0].pop_back();

            ope(x, y);
        }

        while(m[0].size()){
            ll x = m[0].back();
            m[0].pop_back();
            ope(x, n + now);
        }

        while(m[1].size()){
            ll x = m[1].back();
            m[1].pop_back();
            ope(x, n + now);
        }

        out(0);
        for(auto [x, y] : ans){
            out(x + 1, y + 1);
        }
    }else if(n == 3){
        ll ans1 = f(a[0], a[1]);
        ans1 = f(ans1, a[2]);
        ll ans2 = f(a[0], a[2]);
        ans2 = f(ans2, a[1]);
        ll ans3 = f(a[1], a[2]);
        ans3 = f(ans3, a[0]);
        if(ans1 < ans3){
            if(ans1 < ans2){
                out(ans1);
                out(1, 2);
                out(1, 2);
            }else{
                out(ans2);
                out(1, 3);
                out(1, 2);
            }
        }else{
            out(ans3);
            out(2, 3);
            out(1, 2);
        }
    }else{
        out(f(a[0], a[1]));
        out(1, 2);
    }
}

int main(){
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    cout << fixed << setprecision(20);
    
    input();
    solve();
}