# include using namespace std; using ll = long long; using ull = unsigned long long; const double pi = acos(-1); templateconstexpr T inf() { return ::std::numeric_limits::max(); } templateconstexpr T hinf() { return inf() / 2; } template T_char TL(T_char cX) { return tolower(cX); } template T_char TU(T_char cX) { return toupper(cX); } template bool chmin(T& a,T b) { if(a > b){a = b; return true;} return false; } template bool chmax(T& a,T b) { if(a < b){a = b; return true;} return false; } template bool is_sqare(T a) { if(floor(sqrt(a)) * floor(sqrt(a)) == a){ return true; }return false; } int popcnt(unsigned long long n) { int cnt = 0; for (int i = 0; i < 64; i++)if ((n >> i) & 1)cnt++; return cnt; } int d_sum(ll n) { int ret = 0; while (n > 0) { ret += n % 10; n /= 10; }return ret; } int d_cnt(ll n) { int ret = 0; while (n > 0) { ret++; n /= 10; }return ret; } ll gcd(ll a, ll b) { if (b == 0)return a; return gcd(b, a%b); }; ll lcm(ll a, ll b) { ll g = gcd(a, b); return a / g*b; }; template using dijk = priority_queue, greater>; # define all(qpqpq) (qpqpq).begin(),(qpqpq).end() # define UNIQUE(wpwpw) (wpwpw).erase(unique(all((wpwpw))),(wpwpw).end()) # define LOWER(epepe) transform(all((epepe)),(epepe).begin(),TL) # define UPPER(rprpr) transform(all((rprpr)),(rprpr).begin(),TU) # define rep(i,upupu) for(ll i = 0, i##_len = (upupu);(i) < (i##_len);(i)++) # define reps(i,opopo) for(ll i = 1, i##_len = (opopo);(i) <= (i##_len);(i)++) # define len(x) ((ll)(x).size()) # define bit(n) (1LL << (n)) # define pb push_back # define exists(c, e) ((c).find(e) != (c).end()) #ifdef LOCAL # include "_debug_print.hpp" # define debug(...) debug_print::multi_print(#__VA_ARGS__, __VA_ARGS__) #else # define debug(...) (static_cast(0)) #endif struct INIT{ INIT(){ std::ios::sync_with_stdio(false); std::cin.tie(0); cout << fixed << setprecision(20); } }INIT; template class modint { using u64 = std::uint_fast64_t; public: u64 a; constexpr modint(const u64 x = 0) noexcept : a(x % Modulus) {} constexpr u64 &value() noexcept { return a; } constexpr const u64 &value() const noexcept { return a; } constexpr modint operator+(const modint rhs) const noexcept { return modint(*this) += rhs; } constexpr modint operator-(const modint rhs) const noexcept { return modint(*this) -= rhs; } constexpr modint operator*(const modint rhs) const noexcept { return modint(*this) *= rhs; } constexpr modint operator/(const modint rhs) const noexcept { return modint(*this) /= rhs; } constexpr modint &operator+=(const modint rhs) noexcept { a += rhs.a; if (a >= Modulus) { a -= Modulus; } return *this; } constexpr modint &operator-=(const modint rhs) noexcept { if (a < rhs.a) { a += Modulus; } a -= rhs.a; return *this; } constexpr modint &operator*=(const modint rhs) noexcept { a = a * rhs.a % Modulus; return *this; } constexpr modint &operator/=(modint rhs) noexcept { u64 exp = Modulus - 2; while (exp) { if (exp % 2) { *this *= rhs; } rhs *= rhs; exp /= 2; } return *this; } friend std::ostream& operator<<(std::ostream& os, const modint& rhs) { os << rhs.a; return os; } }; using mint = modint<998244353>; void solve(){ int n; cin >> n; vector a(n); for(auto &x : a)cin >> x; mint ans = 0; rep(i, n){ ans += a[i]*(1-a[(i+1)%n]); } ans /= n; cout << ans << endl; } int main(){ int t = 1; //cin >> t; while(t--)solve(); }