#include #include #include #include #include #include template inline bool chmin(T &lhs, const U &rhs) { if (lhs > rhs) { lhs = rhs; return true; } return false; } template inline bool chmax(T &lhs, const U &rhs) { if (lhs < rhs) { lhs = rhs; return true; } return false; } struct range { using itr = int64_t; struct iterator { itr i; constexpr iterator(itr i_) noexcept : i(i_) { } constexpr void operator ++ () noexcept { ++i; } constexpr itr operator * () const noexcept { return i; } constexpr bool operator != (iterator x) const noexcept { return i != x.i; } }; const iterator l, r; constexpr range(itr l_, itr r_) noexcept : l(l_), r(std::max(l_, r_)) { } constexpr iterator begin() const noexcept { return l; } constexpr iterator end() const noexcept { return r; } }; struct revrange { using itr = int64_t; struct iterator { itr i; constexpr iterator(itr i_) noexcept : i(i_) { } constexpr void operator ++ () noexcept { --i; } constexpr itr operator * () const noexcept { return i; } constexpr bool operator != (iterator x) const noexcept { return i != x.i; } }; const iterator l, r; constexpr revrange(itr l_, itr r_) noexcept : l(l_ - 1), r(std::max(l_, r_) - 1) { } constexpr iterator begin() const noexcept { return r; } constexpr iterator end() const noexcept { return l; } }; template class modular { public: using value_type = uint32_t; using max_type = uint64_t; static constexpr value_type mod = Modulus; static constexpr value_type get_mod() { return mod; } static_assert(mod >= 2, "invalid mod :: smaller than 2"); static_assert(mod < (value_type(1) << 31), "invalid mod :: over 2^31"); template static constexpr value_type normalize(T value_) { if (value_ < 0) { value_ = -value_; value_ %= mod; if (value_ == 0) return 0; return mod - value_; } return value_ % mod; } private: value_type value; public: constexpr modular(): value(0) { } template explicit constexpr modular(T value_): value(normalize(value_)) { } template explicit constexpr operator T() { return static_cast(value); } constexpr value_type get() const { return value; } constexpr modular operator - () const { return modular(mod - value); } constexpr modular operator ~ () const { return inverse(); } constexpr value_type &extract() { return value; } constexpr modular inverse() const { return power(mod - 2); } constexpr modular power(max_type exp) const { modular res(1), mult(*this); while (exp > 0) { if (exp & 1) res *= mult; mult *= mult; exp >>= 1; } return res; } constexpr modular operator + (const modular &rhs) const { return modular(*this) += rhs; } constexpr modular& operator += (const modular &rhs) { if ((value += rhs.value) >= mod) value -= mod; return *this; } constexpr modular operator - (const modular &rhs) const { return modular(*this) -= rhs; } constexpr modular& operator -= (const modular &rhs) { if ((value += mod - rhs.value) >= mod) value -= mod; return *this; } constexpr modular operator * (const modular &rhs) const { return modular(*this) *= rhs; } constexpr modular& operator *= (const modular &rhs) { value = (max_type) value * rhs.value % mod; return *this; } constexpr modular operator / (const modular &rhs) const { return modular(*this) /= rhs; } constexpr modular& operator /= (const modular &rhs) { return (*this) *= rhs.inverse(); } constexpr bool zero() const { return value == 0; } constexpr bool operator == (const modular &rhs) const { return value == rhs.value; } constexpr bool operator != (const modular &rhs) const { return value != rhs.value; } friend std::ostream& operator << (std::ostream &stream, const modular &rhs) { return stream << rhs.value; } }; using m32 = modular<1000000007>; using i32 = int32_t; using i64 = int64_t; using u32 = uint32_t; using u64 = uint64_t; constexpr i32 inf32 = (i32(1) << 30) - 1; constexpr i64 inf64 = (i64(1) << 62) - 1; int main() { size_t N; std::cin >> N; std::vector A(N); for (auto &x: A) { std::cin >> x.extract(); } for (auto query: range(1, N)) { std::vector next(A.size() - 1); for (auto i: range(1, A.size())) { next[i - 1] = A[i - 1] + A[i]; } A = next; } std::cout << A.front() << '\n'; return 0; }