// #define _GLIBCXX_DEBUG #pragma GCC optimize("O2,no-stack-protector,unroll-loops,fast-math") #include using namespace std; #define rep(i, n) for (int i = 0; i < int(n); i++) #define per(i, n) for (int i = (n)-1; 0 <= i; i--) #define rep2(i, l, r) for (int i = (l); i < int(r); i++) #define per2(i, l, r) for (int i = (r)-1; int(l) <= i; i--) #define each(e, v) for (auto& e : v) #define MM << " " << #define pb push_back #define eb emplace_back #define all(x) begin(x), end(x) #define rall(x) rbegin(x), rend(x) #define sz(x) (int)x.size() template void print(const vector& v, T x = 0) { int n = v.size(); for (int i = 0; i < n; i++) cout << v[i] + x << (i == n - 1 ? '\n' : ' '); if (v.empty()) cout << '\n'; } using ll = long long; using pii = pair; using pll = pair; template bool chmax(T& x, const T& y) { return (x < y) ? (x = y, true) : false; } template bool chmin(T& x, const T& y) { return (x > y) ? (x = y, true) : false; } template using minheap = std::priority_queue, std::greater>; template using maxheap = std::priority_queue; template int lb(const vector& v, T x) { return lower_bound(begin(v), end(v), x) - begin(v); } template int ub(const vector& v, T x) { return upper_bound(begin(v), end(v), x) - begin(v); } template void rearrange(vector& v) { sort(begin(v), end(v)); v.erase(unique(begin(v), end(v)), end(v)); } // __int128_t gcd(__int128_t a, __int128_t b) { // if (a == 0) // return b; // if (b == 0) // return a; // __int128_t cnt = a % b; // while (cnt != 0) { // a = b; // b = cnt; // cnt = a % b; // } // return b; // } struct Union_Find_Tree { vector data; const int n; int cnt; Union_Find_Tree(int n) : data(n, -1), n(n), cnt(n) {} int root(int x) { if (data[x] < 0) return x; return data[x] = root(data[x]); } int operator[](int i) { return root(i); } bool unite(int x, int y) { x = root(x), y = root(y); if (x == y) return false; if (data[x] > data[y]) swap(x, y); data[x] += data[y], data[y] = x; cnt--; return true; } int size(int x) { return -data[root(x)]; } int count() { return cnt; }; bool same(int x, int y) { return root(x) == root(y); } void clear() { cnt = n; fill(begin(data), end(data), -1); } }; template struct Mod_Int { int x; Mod_Int() : x(0) {} Mod_Int(long long y) : x(y >= 0 ? y % mod : (mod - (-y) % mod) % mod) {} static int get_mod() { return mod; } Mod_Int& operator+=(const Mod_Int& p) { if ((x += p.x) >= mod) x -= mod; return *this; } Mod_Int& operator-=(const Mod_Int& p) { if ((x += mod - p.x) >= mod) x -= mod; return *this; } Mod_Int& operator*=(const Mod_Int& p) { x = (int)(1LL * x * p.x % mod); return *this; } Mod_Int& operator/=(const Mod_Int& p) { *this *= p.inverse(); return *this; } Mod_Int& operator++() { return *this += Mod_Int(1); } Mod_Int operator++(int) { Mod_Int tmp = *this; ++*this; return tmp; } Mod_Int& operator--() { return *this -= Mod_Int(1); } Mod_Int operator--(int) { Mod_Int tmp = *this; --*this; return tmp; } Mod_Int operator-() const { return Mod_Int(-x); } Mod_Int operator+(const Mod_Int& p) const { return Mod_Int(*this) += p; } Mod_Int operator-(const Mod_Int& p) const { return Mod_Int(*this) -= p; } Mod_Int operator*(const Mod_Int& p) const { return Mod_Int(*this) *= p; } Mod_Int operator/(const Mod_Int& p) const { return Mod_Int(*this) /= p; } bool operator==(const Mod_Int& p) const { return x == p.x; } bool operator!=(const Mod_Int& p) const { return x != p.x; } Mod_Int inverse() const { assert(*this != Mod_Int(0)); return pow(mod - 2); } Mod_Int pow(long long k) const { Mod_Int now = *this, ret = 1; for (; k > 0; k >>= 1, now *= now) { if (k & 1) ret *= now; } return ret; } friend ostream& operator<<(ostream& os, const Mod_Int& p) { return os << p.x; } friend istream& operator>>(istream& is, Mod_Int& p) { long long a; is >> a; p = Mod_Int(a); return is; } }; ll mpow2(ll x, ll n, ll mod) { ll ans = 1; x %= mod; while (n != 0) { if (n & 1) ans = ans * x % mod; x = x * x % mod; n = n >> 1; } ans %= mod; return ans; } template T modinv(T a, const T& m) { T b = m, u = 1, v = 0; while (b > 0) { T t = a / b; swap(a -= t * b, b); swap(u -= t * v, v); } return u >= 0 ? u % m : (m - (-u) % m) % m; } ll divide_int(ll a, ll b) { if (b < 0) a = -a, b = -b; return (a >= 0 ? a / b : (a - b + 1) / b); } // const int MOD = 1000000007; const int MOD = 998244353; using mint = Mod_Int; // ----- library ------- // ----- library ------- int main() { ios::sync_with_stdio(false); std::cin.tie(nullptr); cout << fixed << setprecision(15); int si = 2e5 + 10; vector spf(si, -1); rep2(i, 2, si) { if (spf[i] == -1) { for (int j = i; j < si; j += i) spf[j] = i; } } int n; cin >> n; vector a(n); rep(i, n) cin >> a[i]; auto solve = [&](int i, int j) { vector ans; ans.eb(i, j); rep(i, n - 2) ans.eb(0, n - 2 - i); cout << 0 << endl; rep(i, n - 1) cout << ans[i].first + 1 << ' ' << ans[i].second + 1 << '\n'; }; rep(i, n) { if (a[i] <= 1) { solve(i, (i + 1) % n); return 0; } } vector> ls(si); rep(i, n) { int ca = a[i]; while (ca > 1) { int p = spf[ca]; ls[p].eb(i); while (ca % p == 0) ca /= p; } } rep(i, si) { if (sz(ls[i]) >= 2) { solve(ls[i][0], ls[i][1]); return 0; } } auto f = [](ll a, ll b) { if (gcd(a, b) != 1) return 0ll; __int128_t x = __int128_t(a) * b - a - b + 1; if (x > ll(1e18)) return ll(2e18); else return ll(x); }; auto dfs = [&f](vector a, auto &&dfs) ->pair> { if (sz(a) == 1) return pair(a[0], vector{}); ll mi = 3e18; vector ord; rep(i, sz(a)) rep2(j, i + 1, sz(a)) { ll val = f(a[i], a[j]); vector b; rep(k, sz(a)) if (k != i && k != j) b.eb(a[k]); b.eb(val); auto ret = dfs(b, dfs); ret.second.eb(i, j); if (chmin(mi, ret.first)) ord = ret.second; } return pair(mi, ord); }; if (n <= 4) { auto [m, ans] = dfs(a, dfs); cout << m << endl; reverse(all(ans)); each(e, ans) cout << e.first + 1 << ' ' << e.second + 1 << '\n'; } else { exit(1); vector ans; rep(i, n) { if (a[i] % 2 == 0) continue; rep2(j, i + 1, n) { if (a[j] % 2 == 0) continue; rep2(k, j + 1, n) { if (a[k] % 2 == 0) continue; rep2(l, k + 1, n) { if (a[l] % 2 == 0) continue; ans.eb(k, l); ans.eb(i, j); rep(i, n - 3) ans.eb(i, n - 3 - i); cout << 0 << endl; each(e, ans) cout << e.first + 1 << ' ' << e.second + 1 << '\n'; return 0; } } } } } }