#include <bits/stdc++.h>
using namespace std;
using LL = long long int;
#define incII(i, l, r) for(LL i = (l)    ; i <= (r); i++)
#define incIX(i, l, r) for(LL i = (l)    ; i <  (r); i++)
#define incXI(i, l, r) for(LL i = (l) + 1; i <= (r); i++)
#define incXX(i, l, r) for(LL i = (l) + 1; i <  (r); i++)
#define decII(i, l, r) for(LL i = (r)    ; i >= (l); i--)
#define decIX(i, l, r) for(LL i = (r) - 1; i >= (l); i--)
#define decXI(i, l, r) for(LL i = (r)    ; i >  (l); i--)
#define decXX(i, l, r) for(LL i = (r) - 1; i >  (l); i--)
#define inc(i, n)  incIX(i, 0, n)
#define dec(i, n)  decIX(i, 0, n)
#define inc1(i, n) incII(i, 1, n)
#define dec1(i, n) decII(i, 1, n)
auto inII = [](auto x, auto l, auto r) { return (l <= x && x <= r); };
auto inIX = [](auto x, auto l, auto r) { return (l <= x && x <  r); };
auto inXI = [](auto x, auto l, auto r) { return (l <  x && x <= r); };
auto inXX = [](auto x, auto l, auto r) { return (l <  x && x <  r); };
auto setmin   = [](auto & a, auto b) { return (b <  a ? a = b, true : false); };
auto setmax   = [](auto & a, auto b) { return (b >  a ? a = b, true : false); };
auto setmineq = [](auto & a, auto b) { return (b <= a ? a = b, true : false); };
auto setmaxeq = [](auto & a, auto b) { return (b >= a ? a = b, true : false); };
#define PB push_back
#define EB emplace_back
#define MP make_pair
#define MT make_tuple
#define FI first
#define SE second
#define FR front()
#define BA back()
#define ALL(c) c.begin(), c.end()
#define RALL(c) c.rbegin(), c.rend()
#define RV(c) reverse(ALL(c))
#define SC static_cast
#define SI(c) SC<int>(c.size())
#define SL(c) SC<LL >(c.size())
#define RF(e, c) for(auto & e: c)
#define SF(c, ...) for(auto & [__VA_ARGS__]: c)
#define until(e) while(! (e))
#define if_not(e) if(! (e))
#define ef else if
#define UR assert(false)
auto * IS = & cin;
auto * OS = & cout;
array<string, 3> SEQ = { "", " ", "" };
// input
template<typename T> T in() { T a; (* IS) >> a; return a; }
// input: tuple
template<int I, typename U> void tin_(istream & is, U & t) {
	if constexpr(I < tuple_size<U>::value) { is >> get<I>(t); tin_<I + 1>(is, t); }
}
template<typename ... T> istream & operator>>(istream & is, tuple<T ...> & t) { tin_<0>(is, t); return is; }
template<typename ... T> auto tin() { return in<tuple<T ...>>(); }
// input: array
template<typename T, size_t N> istream & operator>>(istream & is, array<T, N> & a) { RF(e, a) { is >> e; } return is; }
template<typename T, size_t N> auto ain() { return in<array<T, N>>(); }
// input: multi-dimensional vector
template<typename T> T vin() { T v; (* IS) >> v; return v; }
template<typename T, typename N, typename ... M> auto vin(N n, M ... m) {
	vector<decltype(vin<T, M ...>(m ...))> v(n); inc(i, n) { v[i] = vin<T, M ...>(m ...); } return v;
}
// input: multi-column (tuple<vector>)
template<typename U, int I> void colin_([[maybe_unused]] U & t) { }
template<typename U, int I, typename A, typename ... B> void colin_(U & t) {
	get<I>(t).PB(in<A>()); colin_<U, I + 1, B ...>(t);
}
template<typename ... T> auto colin(int n) {
	tuple<vector<T> ...> t; inc(i, n) { colin_<tuple<vector<T> ...>, 0, T ...>(t); } return t;
}
// output
void out_([[maybe_unused]] string s) { }
template<typename A> void out_([[maybe_unused]] string s, A && a) { (* OS) << a; }
template<typename A, typename ... B> void out_(string s, A && a, B && ... b) { (* OS) << a << s; out_(s, b ...); }
auto outF = [](auto x, auto y, auto z, auto ... a) { (* OS) << x; out_(y, a ...); (* OS) << z << flush; };
auto out  = [](auto ... a) { outF("", " " , "\n", a ...); };
auto outS = [](auto ... a) { outF("", " " , " " , a ...); };
auto outL = [](auto ... a) { outF("", "\n", "\n", a ...); };
auto outN = [](auto ... a) { outF("", ""  , ""  , a ...); };
// output: multi-dimensional vector
template<typename T> ostream & operator<<(ostream & os, vector<T> const & v) {
	os << SEQ[0]; inc(i, SI(v)) { os << (i == 0 ? "" : SEQ[1]) << v[i]; } return (os << SEQ[2]);
}
template<typename T> void vout_(T && v) { (* OS) << v; }
template<typename T, typename A, typename ... B> void vout_(T && v, A a, B ... b) {
	inc(i, SI(v)) { (* OS) << (i == 0 ? "" : a); vout_(v[i], b ...); }
}
template<typename T, typename A, typename ... B> void vout (T && v, A a, B ... b) { vout_(v, a, b ...); (* OS) << a << flush; }
template<typename T, typename A, typename ... B> void voutN(T && v, A a, B ... b) { vout_(v, a, b ...); (* OS)      << flush; }

// ---- ----

template<LL M> class ModInt {
private:
	LL v;
	pair<LL, LL> ext_gcd(LL a, LL b) {
		if(b == 0) { assert(a == 1); return { 1, 0 }; }
		auto p = ext_gcd(b, a % b);
		return { p.SE, p.FI - (a / b) * p.SE };
	}
public:
	ModInt(LL vv = 0) { v = vv; if(abs(v) >= M) { v %= M; } if(v < 0) { v += M; } }
	LL val() { return v; }
	static LL mod() { return M; }
	ModInt inv() { return ext_gcd(M, v).SE; }
	ModInt exp(LL b) {
		ModInt p = 1, a = v; if(b < 0) { a = a.inv(); b = -b; }
		while(b) { if(b & 1) { p *= a; } a *= a; b >>= 1; }
		return p;
	}
	friend bool      operator< (ModInt    a, ModInt   b) { return (a.v <  b.v); }
	friend bool      operator> (ModInt    a, ModInt   b) { return (a.v >  b.v); }
	friend bool      operator<=(ModInt    a, ModInt   b) { return (a.v <= b.v); }
	friend bool      operator>=(ModInt    a, ModInt   b) { return (a.v >= b.v); }
	friend bool      operator==(ModInt    a, ModInt   b) { return (a.v == b.v); }
	friend bool      operator!=(ModInt    a, ModInt   b) { return (a.v != b.v); }
	friend ModInt    operator+ (ModInt    a            ) { return ModInt(+a.v); }
	friend ModInt    operator- (ModInt    a            ) { return ModInt(-a.v); }
	friend ModInt    operator+ (ModInt    a, ModInt   b) { return ModInt(a.v + b.v); }
	friend ModInt    operator- (ModInt    a, ModInt   b) { return ModInt(a.v - b.v); }
	friend ModInt    operator* (ModInt    a, ModInt   b) { return ModInt(a.v * b.v); }
	friend ModInt    operator/ (ModInt    a, ModInt   b) { return a * b.inv(); }
	friend ModInt    operator^ (ModInt    a, LL       b) { return a.exp(b); }
	friend ModInt  & operator+=(ModInt  & a, ModInt   b) { return (a = a + b); }
	friend ModInt  & operator-=(ModInt  & a, ModInt   b) { return (a = a - b); }
	friend ModInt  & operator*=(ModInt  & a, ModInt   b) { return (a = a * b); }
	friend ModInt  & operator/=(ModInt  & a, ModInt   b) { return (a = a / b); }
	friend ModInt  & operator^=(ModInt  & a, LL       b) { return (a = a ^ b); }
	friend istream & operator>>(istream & s, ModInt & b) { s >> b.v; b = ModInt(b.v); return s; }
	friend ostream & operator<<(ostream & s, ModInt   b) { return (s << b.v); }
};

// ----

template<typename C, int N> class Poly {
private:
	using D = array<int, N>;
	using P = map<D, C>;
	P p;
	static D plus(D a, D b) {
		D d = { };
		inc(i, N) { d[i] = a[i] + b[i]; }
		return d;
	}
	Poly sum_of_power(int k, int i) { // sum x_i in [0, x_i] x_i ^ k
		int L = k + 2;
		vector<C> c(L);
		inc(j, L) { c[j] = C(j) ^ k; }
		inc(j, L - 1) { c[j + 1] += c[j]; }
		Poly v;
		inc(a, L) {
			Poly w = c[a];
			inc(b, L) {
				if(a == b) { continue; }
				w *= (x_(i) - C(b)) / C(a - b);
			}
			v += w;
		}
		return v;
	}
public:
	Poly(P pp = { }) { p = pp; }
	Poly(C  c) { p = { { { }, c } }; }
	Poly(LL c) { p = { { { }, c } }; }
	static Poly x_(int i) {
		D d = { };
		d[i] = 1;
		return Poly({ { d, 1 } });
	}
	C substitute(array<C, N> x) {
		C v = 0;
		RF(t, p) {
			C w = t.SE;
			inc(i, N) { w *= x[i] ^ t.FI[i]; }
			v += w;
		}
		return v;
	}
	Poly sum() {
		Poly v;
		RF(t, p) {
			Poly w = t.SE;
			inc(i, N) { w *= sum_of_power(t.FI[i], i); }
			v += w;
		}
		return v;
	}
	friend Poly operator+(Poly a, Poly b) { RF(t, b.p) { a.p[t.FI] += t.SE; } return a; }
	friend Poly operator-(Poly a, Poly b) { RF(t, b.p) { a.p[t.FI] -= t.SE; } return a; }
	friend Poly operator/(Poly a, C    b) { RF(t, a.p) { t.SE /= b; } return a; }
	friend Poly operator*(Poly a, Poly b) {
		P pp;
		RF(ta, a.p) {
		RF(tb, b.p) {
			pp[plus(ta.FI, tb.FI)] += ta.SE * tb.SE;
		}
		}
		return Poly(pp);
	}
	friend Poly & operator+=(Poly & a, Poly b) { return (a = a + b); }
	friend Poly & operator-=(Poly & a, Poly b) { return (a = a - b); }
	friend Poly & operator/=(Poly & a, C    b) { return (a = a / b); }
	friend Poly & operator*=(Poly & a, Poly b) { return (a = a * b); }
	friend ostream & operator<<(ostream & os, Poly b) {
		RF(t, b.p) {
			if(t.SE == 0) { continue; }
			os << t.SE;
			inc(i, N) {
				if(t.FI[i] == 0) { continue; }
				os << " " << SC<char>('x' + i);
				if(t.FI[i] == 1) { continue; }
				os << "^" << t.FI[i];
			}
			os << endl;
		}
		return os;
	}
};

// ----

using MI = ModInt<998244353>;

int main() {
	auto n = in<int>();
	auto [t, v] = colin<MI, MI>(n);
	vector<MI> L(n), R(n);
	inc(i, n - 1) { L[i + 1] = L[i] + t[i]; }
	dec(i, n - 1) { R[i] = R[i + 1] + t[i + 1]; }
	
	auto x = Poly<MI, 1>::x_(0);
	MI ans = 0;
	inc(i, n) {
		auto p = v[i] * (R[i] + t[i] - x) * (L[i] + x + 1) * (L[i] + x + 2) / 2;
		ans += p.sum().substitute({ t[i] - 1 });
	}
	out(ans);
}