/* #region Head */ #include using namespace std; using ll = long long; using ull = unsigned long long; using ld = long double; using pll = pair; template using vc = vector; template using vvc = vc>; using vll = vc; using vvll = vvc; using vld = vc; using vvld = vvc; using vs = vc; using vvs = vvc; template using um = unordered_map; template using pq = priority_queue; template using pqa = priority_queue, greater>; template using us = unordered_set; #define REP(i, m, n) for (ll i = (m), i##_len = (ll)(n); i < i##_len; ++(i)) #define REPM(i, m, n) for (ll i = (m), i##_max = (ll)(n); i <= i##_max; ++(i)) #define REPR(i, m, n) for (ll i = (m), i##_min = (ll)(n); i >= i##_min; --(i)) #define REPD(i, m, n, d) for (ll i = (m), i##_len = (ll)(n); i < i##_len; i += (d)) #define REPMD(i, m, n, d) for (ll i = (m), i##_max = (ll)(n); i <= i##_max; i += (d)) #define REPI(itr, ds) for (auto itr = ds.begin(); itr != ds.end(); itr++) #define ALL(x) begin(x), end(x) #define SIZE(x) ((ll)(x).size()) #define PERM(c) \ sort(ALL(c)); \ for (bool c##p = 1; c##p; c##p = next_permutation(ALL(c))) #define UNIQ(v) v.erase(unique(ALL(v)), v.end()); #define endl '\n' #define sqrt sqrtl #define floor floorl #define log2 log2l constexpr ll INF = 1'010'000'000'000'000'017LL; constexpr ll MOD = 1'000'000'007LL; // 1e9 + 7 constexpr ld EPS = 1e-12; constexpr ld PI = 3.14159265358979323846; template istream &operator>>(istream &is, vc &vec) { // vector 入力 for (T &x : vec) is >> x; return is; } template ostream &operator<<(ostream &os, vc &vec) { // vector 出力 (for dump) os << "{"; REP(i, 0, SIZE(vec)) os << vec[i] << (i == i_len - 1 ? "" : ", "); os << "}"; return os; } template ostream &operator>>(ostream &os, vc &vec) { // vector 出力 (inline) REP(i, 0, SIZE(vec)) os << vec[i] << (i == i_len - 1 ? "\n" : " "); return os; } template istream &operator>>(istream &is, pair &pair_var) { // pair 入力 is >> pair_var.first >> pair_var.second; return is; } template ostream &operator<<(ostream &os, pair &pair_var) { // pair 出力 os << "(" << pair_var.first << ", " << pair_var.second << ")"; return os; } // map, um, set, us 出力 template ostream &out_iter(ostream &os, T &map_var) { os << "{"; REPI(itr, map_var) { os << *itr; auto itrcp = itr; if (++itrcp != map_var.end()) os << ", "; } return os << "}"; } template ostream &operator<<(ostream &os, map &map_var) { return out_iter(os, map_var); } template ostream &operator<<(ostream &os, um &map_var) { os << "{"; REPI(itr, map_var) { auto [key, value] = *itr; os << "(" << key << ", " << value << ")"; auto itrcp = itr; if (++itrcp != map_var.end()) os << ", "; } os << "}"; return os; } template ostream &operator<<(ostream &os, set &set_var) { return out_iter(os, set_var); } template ostream &operator<<(ostream &os, us &set_var) { return out_iter(os, set_var); } template ostream &operator<<(ostream &os, pq &pq_var) { pq pq_cp(pq_var); os << "{"; if (!pq_cp.empty()) { os << pq_cp.top(), pq_cp.pop(); while (!pq_cp.empty()) os << ", " << pq_cp.top(), pq_cp.pop(); } return os << "}"; } // dump #define DUMPOUT cerr void dump_func() { DUMPOUT << endl; } template void dump_func(Head &&head, Tail &&... tail) { DUMPOUT << head; if (sizeof...(Tail) > 0) DUMPOUT << ", "; dump_func(move(tail)...); } // chmax (更新「される」かもしれない値が前) template > bool chmax(T &xmax, const U &x, Comp comp = {}) { if (comp(xmax, x)) { xmax = x; return true; } return false; } // chmin (更新「される」かもしれない値が前) template > bool chmin(T &xmin, const U &x, Comp comp = {}) { if (comp(x, xmin)) { xmin = x; return true; } return false; } // ローカル用 #define DEBUG_ #ifdef DEBUG_ #define DEB #define dump(...) \ DUMPOUT << " " << string(#__VA_ARGS__) << ": " \ << "[" << to_string(__LINE__) << ":" << __FUNCTION__ << "]" << endl \ << " ", \ dump_func(__VA_ARGS__) #else #define DEB if (false) #define dump(...) #endif struct AtCoderInitialize { static constexpr int IOS_PREC = 15; static constexpr bool AUTOFLUSH = false; AtCoderInitialize() { ios_base::sync_with_stdio(false), cin.tie(nullptr), cout.tie(nullptr); cout << fixed << setprecision(IOS_PREC); if (AUTOFLUSH) cout << unitbuf; } } ATCODER_INITIALIZE; void Yn(bool p) { cout << (p ? "Yes" : "No") << endl; } void YN(bool p) { cout << (p ? "YES" : "NO") << endl; } /* #endregion */ /* #region mint */ // 自動で MOD を取る整数 struct mint { ll x; mint(ll x = 0) : x((x % MOD + MOD) % MOD) {} mint &operator+=(const mint a) { if ((x += a.x) >= MOD) x -= MOD; return *this; } mint &operator-=(const mint a) { if ((x += MOD - a.x) >= MOD) x -= MOD; return *this; } mint &operator*=(const mint a) { (x *= a.x) %= MOD; return *this; } mint operator+(const mint a) const { mint res(*this); return res += a; } mint operator-(const mint a) const { mint res(*this); return res -= a; } mint operator*(const mint a) const { mint res(*this); return res *= a; } // O(log(t)) mint pow(ll t) const { if (!t) return 1; mint a = pow(t >> 1); // ⌊t/2⌋ 乗 a *= a; // ⌊t/2⌋*2 乗 if (t & 1) // ⌊t/2⌋*2 == t-1 のとき a *= *this; // ⌊t/2⌋*2+1 乗 => t 乗 return a; } // for prime mod mint inv() const { return pow(MOD - 2); // オイラーの定理から, x^(-1) ≡ x^(p-2) } mint &operator/=(const mint a) { return (*this) *= a.inv(); } mint operator/(const mint a) const { mint res(*this); return res /= a; } bool operator==(const mint a) const { return this->x == a.x; } bool operator==(const ll a) const { return this->x == a; } // mint 入力 friend istream &operator>>(istream &is, mint &x) { is >> x.x; return is; } // mint 出力 friend ostream &operator<<(ostream &os, mint x) { os << x.x; return os; } }; /* #endregion */ /* #region SegTree */ template // T: 要素 struct SegmentTree { using F = function; // 要素と要素をマージする関数.max とか. ll n; // 木のノード数 F f; // 区間クエリで使う演算,結合法則を満たす演算.区間最大値のクエリを投げたいなら max 演算. T ti; // 値配列の初期値.演算 f に関する単位元.区間最大値なら単位元は 0. (a>0 なら max(a,0)=max(0,a)=a) vc dat; // 1-indexed 値配列 (index は木の根から順に 1 | 2 3 | 4 5 6 7 | 8 9 10 11 12 13 14 15 | ...) // コンストラクタ. SegmentTree() {} // コンストラクタ. SegmentTree(F f, T ti) : f(f), ti(ti) {} // 指定要素数のセグメント木を初期化する void init(ll n_) { n = 1; while (n < n_) n <<= 1; dat.assign(n << 1, ti); } // ベクトルからセグメント木を構築する void build(const vc &v) { ll n_ = v.size(); init(n_); REP(i, 0, n_) dat[n + i] = v[i]; REPR(i, n - 1, 1) dat[i] = f(dat[(i << 1) | 0], dat[(i << 1) | 1]); } // インデックス k の要素の値を x にする. void set_val(ll k, T x) { dat[k += n] = x; while (k >>= 1) dat[k] = f(dat[(k << 1) | 0], dat[(k << 1) | 1]); // 上へ登って更新していく } // インデックス k の要素の値を取得する. T get_val(ll k) { return dat[k + n]; } // 半開区間 [a, b) に対するクエリを実行する T query(ll a, ll b) { if (a >= b) return ti; // assert(a>= 1, r >>= 1) { if (l & 1) vl = f(vl, dat[l++]); if (r & 1) vr = f(dat[--r], vr); } return f(vl, vr); } // セグメント木上の二分探索 template int find(ll st, C &check, T &acc, ll k, ll l, ll r) { if (l + 1 == r) { acc = f(acc, dat[k]); return check(acc) ? k - n : -1; } ll m = (l + r) >> 1; if (m <= st) return find(st, check, acc, (k << 1) | 1, m, r); if (st <= l && !check(f(acc, dat[k]))) { acc = f(acc, dat[k]); return -1; } ll vl = find(st, check, acc, (k << 1) | 0, l, m); if (~vl) return vl; return find(st, check, acc, (k << 1) | 1, m, r); } // セグメント木上の二分探索.check(query(st, idx)) が真となる idx を返す. template int find(ll st, C &check) { T acc = ti; return find(st, check, acc, 1, 0, n); } }; /* #endregion */ template ll binarySearchIntMax(ll left, ll right, tProposition p) { if (right < left) return -1; ll mid; while (left + 1 < right) { mid = (left + right) / 2; if (p(mid)) left = mid; else // fn > 0 right = mid - 1; } if (p(right)) return right; else if (p(left)) return left; else return -1; } // Problem void solve() { ll n; cin >> n; vll a(n); cin >> a; REP(i, 0, n) if (a[i] == 0) { cout << 0 << endl; return; } ll t = (ll)1e9; auto f = [&t](ll a, ll b) -> ll { ll m = a * b; if (m >= t) m = t; return m; }; SegmentTree seg(f, 1); seg.build(a); // 区間積を返す mint ret = 1; ll infl = 0; ll cnt = 0; vll imos(n + 1, 0); REP(left, 0, n) { ll max_idx_of_safe = binarySearchIntMax(left, n - 1, [&](ll right) { return seg.query(left, right + 1) < t; // t 未満 }); imos[max_idx_of_safe + 1]++; ll len = max_idx_of_safe - left + 1; cnt++; cnt -= imos[left]; infl += len; ret *= mint(a[left]).pow(infl); // dump(left, max_idx_of_safe, len, ret); infl -= cnt; } cout << ret << endl; } // entry point int main() { solve(); return 0; }