#include "bits/stdc++.h"
#ifndef ONLINE_JUDGE
#include "headers/debug.h"
#else
#define debug(...) 42
#endif

using namespace std;

#define all(x) x.begin(), x.end()
#define ff first
#define ss second
#define LLINF 0x3f3f3f3f3f3f3f3f
#define INF 0x3f3f3f3f
#define uniq(x) sort(all(x)); x.resize(unique(all(x))-x.begin());
#define sz(x) (int)x.size()
#define pw(x) (1LL<<x)
#define pb push_back

using pii = pair<int, int>;
using ll = long long;
using ld = long double;
const ll MOD = 1e9 + 7;
const long double PI = acos(-1.0);

template <typename T>
T inverse(T a, T m) {
	T u = 0, v = 1;
	while (a != 0) {
		T t = m / a;
		m -= t * a; swap(a, m);
		u -= t * v; swap(u, v);
	}
	assert(m == 1);
	return u;
}
template <typename T>
class Modular {
public:
	using Type = typename decay<decltype(T::value)>::type;
	constexpr Modular() : value() {}
template <typename U>
	Modular(const U& x) {
		value = normalize(x);
	}
template <typename U>
	static Type normalize(const U& x) {
		Type v;
		if (-mod() <= x && x < mod()) v = static_cast<Type>(x);
		else v = static_cast<Type>(x % mod());
		if (v < 0) v += mod();
		return v;
	}
	const Type& operator()() const { return value; }
template <typename U>
	explicit operator U() const { return static_cast<U>(value); }
	constexpr static Type mod() { return T::value; }
	Modular& operator+=(const Modular& other) { if ((value += other.value) >= mod()) value -= mod(); return *this; }
	Modular& operator-=(const Modular& other) { if ((value -= other.value) < 0) value += mod(); return *this; }
template <typename U> Modular& operator+=(const U& other) { return *this += Modular(other); }
template <typename U> Modular& operator-=(const U& other) { return *this -= Modular(other); }
	Modular& operator++() { return *this += 1; }
	Modular& operator--() { return *this -= 1; }
	Modular operator++(int) { Modular result(*this); *this += 1; return result; }
	Modular operator--(int) { Modular result(*this); *this -= 1; return result; }
	Modular operator-() const { return Modular(-value); }
template <typename U = T>
	typename enable_if<is_same<typename Modular<U>::Type, int>::value, Modular>::type& operator*=(const Modular& rhs) {
#ifdef _WIN32
		uint64_t x = static_cast<int64_t>(value) * static_cast<int64_t>(rhs.value);
		uint32_t xh = static_cast<uint32_t>(x >> 32), xl = static_cast<uint32_t>(x), d, m;
		asm(
			"divl %4; \n\t"
			: "=a" (d), "=d" (m)
			: "d" (xh), "a" (xl), "r" (mod())
			);
		value = m;
#else
		value = normalize(static_cast<int64_t>(value) * static_cast<int64_t>(rhs.value));
#endif
		return *this;
	}
template <typename U = T>
	typename enable_if<is_same<typename Modular<U>::Type, int64_t>::value, Modular>::type& operator*=(const Modular& rhs) {
		int64_t q = static_cast<int64_t>(static_cast<long double>(value) * rhs.value / mod());
		value = normalize(value * rhs.value - q * mod());
		return *this;
	}
template <typename U = T>
	typename enable_if<!is_integral<typename Modular<U>::Type>::value, Modular>::type& operator*=(const Modular& rhs) {
		value = normalize(value * rhs.value);
		return *this;
	}
	Modular& operator/=(const Modular& other) { return *this *= Modular(inverse(other.value, mod())); }
template <typename U>
	friend bool operator==(const Modular<U>& lhs, const Modular<U>& rhs);
template <typename U>
	friend bool operator<(const Modular<U>& lhs, const Modular<U>& rhs);
template <typename U>
	friend std::istream& operator>>(std::istream& stream, Modular<U>& number);
private:
	Type value;
};
template <typename T> bool operator==(const Modular<T>& lhs, const Modular<T>& rhs) { return lhs.value == rhs.value; }
template <typename T, typename U> bool operator==(const Modular<T>& lhs, U rhs) { return lhs == Modular<T>(rhs); }
template <typename T, typename U> bool operator==(U lhs, const Modular<T>& rhs) { return Modular<T>(lhs) == rhs; }
template <typename T> bool operator!=(const Modular<T>& lhs, const Modular<T>& rhs) { return !(lhs == rhs); }
template <typename T, typename U> bool operator!=(const Modular<T>& lhs, U rhs) { return !(lhs == rhs); }
template <typename T, typename U> bool operator!=(U lhs, const Modular<T>& rhs) { return !(lhs == rhs); }
template <typename T> bool operator<(const Modular<T>& lhs, const Modular<T>& rhs) { return lhs.value < rhs.value; }
template <typename T> Modular<T> operator+(const Modular<T>& lhs, const Modular<T>& rhs) { return Modular<T>(lhs) += rhs; }
template <typename T, typename U> Modular<T> operator+(const Modular<T>& lhs, U rhs) { return Modular<T>(lhs) += rhs; }
template <typename T, typename U> Modular<T> operator+(U lhs, const Modular<T>& rhs) { return Modular<T>(lhs) += rhs; }
template <typename T> Modular<T> operator-(const Modular<T>& lhs, const Modular<T>& rhs) { return Modular<T>(lhs) -= rhs; }
template <typename T, typename U> Modular<T> operator-(const Modular<T>& lhs, U rhs) { return Modular<T>(lhs) -= rhs; }
template <typename T, typename U> Modular<T> operator-(U lhs, const Modular<T>& rhs) { return Modular<T>(lhs) -= rhs; }
template <typename T> Modular<T> operator*(const Modular<T>& lhs, const Modular<T>& rhs) { return Modular<T>(lhs) *= rhs; }
template <typename T, typename U> Modular<T> operator*(const Modular<T>& lhs, U rhs) { return Modular<T>(lhs) *= rhs; }
template <typename T, typename U> Modular<T> operator*(U lhs, const Modular<T>& rhs) { return Modular<T>(lhs) *= rhs; }
template <typename T> Modular<T> operator/(const Modular<T>& lhs, const Modular<T>& rhs) { return Modular<T>(lhs) /= rhs; }
template <typename T, typename U> Modular<T> operator/(const Modular<T>& lhs, U rhs) { return Modular<T>(lhs) /= rhs; }
template <typename T, typename U> Modular<T> operator/(U lhs, const Modular<T>& rhs) { return Modular<T>(lhs) /= rhs; }
template<typename T, typename U>
Modular<T> power(const Modular<T>& a, const U& b) {
	assert(b >= 0);
	Modular<T> x = a, res = 1;
	U p = b;
	while (p > 0) {
		if (p & 1) res *= x;
		x *= x;
		p >>= 1;
	}
	return res;
}
template <typename T>
string to_string(const Modular<T>& number) {
	return to_string(number());
}
template <typename T>
std::ostream& operator<<(std::ostream& stream, const Modular<T>& number) {
	return stream << number();
}
template <typename T>
std::istream& operator>>(std::istream& stream, Modular<T>& number) {
	typename common_type<typename Modular<T>::Type, int64_t>::type x;
	stream >> x;
	number.value = Modular<T>::normalize(x);
	return stream;
}
/*
using ModType = int;
struct VarMod { static ModType value; };
ModType VarMod::value;
ModType& md = VarMod::value;
using mint = Modular<VarMod>;
*/
constexpr int md = 998244353;
using mint = Modular<std::integral_constant<decay<decltype(md)>::type, md>>;

int main() {
	ios::sync_with_stdio(0), cin.tie(0);
	int n;cin>>n;
	vector<int> a(n);
	for(int i=0;i<n;i++){
		cin>>a[i];
	}
	mint ans=(mint)0;
	for(int i=1;i<n;i++){
		ans-=(power((mint)2,i)-1)*a[i];
	}
	for(int i=0;i<n-1;i++){
		ans+=(power((mint)2,n-i-1)-1)*a[i];
	}
	cout<<ans<<'\n';
}