Leha is planning his journey from Moscow to Saratov. He hates trains, so he has decided to get from one city to another by car.

The path from Moscow to Saratov can be represented as a straight line (well, it's not that straight in reality, but in this problem we will consider it to be straight), and the distance between Moscow and Saratov is $n$ km. Let's say that Moscow is situated at the point with coordinate $0$ km, and Saratov — at coordinate $n$ km.

Driving for a long time may be really difficult. Formally, if Leha has already covered $i$ kilometers since he stopped to have a rest, he considers the difficulty of covering $(i + 1)$-th kilometer as $a_{i + 1}$. It is guaranteed that for every $i \in [1, n - 1]$ $a_i \le a_{i + 1}$. The difficulty of the journey is denoted as the sum of difficulties of each kilometer in the journey.

Fortunately, there may be some rest sites between Moscow and Saratov. Every integer point from $1$ to $n - 1$ may contain a rest site. When Leha enters a rest site, he may have a rest, and the next kilometer will have difficulty $a_1$, the kilometer after it — difficulty $a_2$, and so on.

For example, if $n = 5$ and there is a rest site in coordinate $2$, the difficulty of journey will be $2a_1 + 2a_2 + a_3$: the first kilometer will have difficulty $a_1$, the second one — $a_2$, then Leha will have a rest, and the third kilometer will have difficulty $a_1$, the fourth — $a_2$, and the last one — $a_3$. Another example: if $n = 7$ and there are rest sites in coordinates $1$ and $5$, the difficulty of Leha's journey is $3a_1 + 2a_2 + a_3 + a_4$.

Leha doesn't know which integer points contain rest sites. So he has to consider every possible situation. Obviously, there are $2^{n - 1}$ different distributions of rest sites (two distributions are different if there exists some point $x$ such that it contains a rest site in exactly one of these distributions). Leha considers all these distributions to be equiprobable. He wants to calculate $p$ — the expected value of difficulty of his journey.

Obviously, $p \cdot 2^{n - 1}$ is an integer number. You have to calculate it modulo $998244353$.
The first line contains one number $n$ ($1 \le n \le 10^6$) — the distance from Moscow to Saratov.

The second line contains $n$ integer numbers $a_1$, $a_2$, ..., $a_n$ ($1 \le a_1 \le a_2 \le \dots \le a_n \le 10^6$), where $a_i$ is the difficulty of $i$-th kilometer after Leha has rested.
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1 3 3 7
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3 3 3 4 7 8 8 8 9 9 10 12 12 13 14 14 15 15 16 17 17 20 21 21 22 22 23 25 29 31 36 37 37 38 39 40 41 41 41 42 43 44 45 46 46 47 47 49 49 49 51 52 52 53 54 55 59 59 59 60 62 63 63 64 66 69 70 71 71 72 74 76 76 77 77 78 78 79 80 81 81 82 82 84 85 86 87 87 87 89 91 92 92 92 92 97 98 99 100 100
758086002
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#Code by Sounak, IIESTS
#------------------------------warmup----------------------------

import os
import sys
import math
from io import BytesIO, IOBase
import io
from fractions import Fraction
import collections
from itertools import permutations
from collections import defaultdict
from collections import deque
import threading

#sys.setrecursionlimit(300000)
#threading.stack_size(10**8)

BUFSIZE = 8192
 
 
class FastIO(IOBase):
    newlines = 0
    
    def __init__(self, file):
        self._fd = file.fileno()
        self.buffer = BytesIO()
        self.writable = "x" in file.mode or "r" not in file.mode
        self.write = self.buffer.write if self.writable else None
     
    def read(self):
        while True:
            b = os.read(self._fd, max(os.fstat(self._fd).st_size, BUFSIZE))
            if not b:
                break
            ptr = self.buffer.tell()
            self.buffer.seek(0, 2), self.buffer.write(b), self.buffer.seek(ptr)
        self.newlines = 0
        return self.buffer.read()
 
    def readline(self):
        while self.newlines == 0:
            b = os.read(self._fd, max(os.fstat(self._fd).st_size, BUFSIZE))
            self.newlines = b.count(b"\n") + (not b)
            ptr = self.buffer.tell()
            self.buffer.seek(0, 2), self.buffer.write(b), self.buffer.seek(ptr)
        self.newlines -= 1
        return self.buffer.readline()
 
    def flush(self):
        if self.writable:
            os.write(self._fd, self.buffer.getvalue())
            self.buffer.truncate(0), self.buffer.seek(0)
 
 
class IOWrapper(IOBase):
    def __init__(self, file):
        self.buffer = FastIO(file)
        self.flush = self.buffer.flush
        self.writable = self.buffer.writable
        self.write = lambda s: self.buffer.write(s.encode("ascii"))
        self.read = lambda: self.buffer.read().decode("ascii")
        self.readline = lambda: self.buffer.readline().decode("ascii")
  
sys.stdin, sys.stdout = IOWrapper(sys.stdin), IOWrapper(sys.stdout)
input = lambda: sys.stdin.readline().rstrip("\r\n")

#-------------------------------------------------------------------------
#mod = 9223372036854775807  
class SegmentTree:
    def __init__(self, data, default=0, func=lambda a, b: a+b):
        """initialize the segment tree with data"""
        self._default = default
        self._func = func
        self._len = len(data)
        self._size = _size = 1 << (self._len - 1).bit_length()
 
        self.data = [default] * (2 * _size)
        self.data[_size:_size + self._len] = data
        for i in reversed(range(_size)):
            self.data[i] = func(self.data[i + i], self.data[i + i + 1])
 
    def __delitem__(self, idx):
        self[idx] = self._default
 
    def __getitem__(self, idx):
        return self.data[idx + self._size]
 
    def __setitem__(self, idx, value):
        idx += self._size
        self.data[idx] = value
        idx >>= 1
        while idx:
            self.data[idx] = self._func(self.data[2 * idx], self.data[2 * idx + 1])
            idx >>= 1
 
    def __len__(self):
        return self._len
 
    def query(self, start, stop):
        if start == stop:
            return self.__getitem__(start)
        stop += 1
        start += self._size
        stop += self._size
 
        res = self._default
        while start < stop:
            if start & 1:
                res = self._func(res, self.data[start])
                start += 1
            if stop & 1:
                stop -= 1
                res = self._func(res, self.data[stop])
            start >>= 1
            stop >>= 1
        return res
 
    def __repr__(self):
        return "SegmentTree({0})".format(self.data)
    
class SegmentTree1:
    def __init__(self, data, default=10**6, func=lambda a, b: min(a,b)):
        """initialize the segment tree with data"""
        self._default = default
        self._func = func
        self._len = len(data)
        self._size = _size = 1 << (self._len - 1).bit_length()
 
        self.data = [default] * (2 * _size)
        self.data[_size:_size + self._len] = data
        for i in reversed(range(_size)):
            self.data[i] = func(self.data[i + i], self.data[i + i + 1])
 
    def __delitem__(self, idx):
        self[idx] = self._default
 
    def __getitem__(self, idx):
        return self.data[idx + self._size]
 
    def __setitem__(self, idx, value):
        idx += self._size
        self.data[idx] = value
        idx >>= 1
        while idx:
            self.data[idx] = self._func(self.data[2 * idx], self.data[2 * idx + 1])
            idx >>= 1
 
    def __len__(self):
        return self._len
 
    def query(self, start, stop):
        if start == stop:
            return self.__getitem__(start)
        stop += 1
        start += self._size
        stop += self._size
 
        res = self._default
        while start < stop:
            if start & 1:
                res = self._func(res, self.data[start])
                start += 1
            if stop & 1:
                stop -= 1
                res = self._func(res, self.data[stop])
            start >>= 1
            stop >>= 1
        return res
 
    def __repr__(self):
        return "SegmentTree({0})".format(self.data)
    
MOD=10**9+7
class Factorial:
    def __init__(self, MOD):
        self.MOD = MOD
        self.factorials = [1, 1]
        self.invModulos = [0, 1]
        self.invFactorial_ = [1, 1]
 
    def calc(self, n):
        if n <= -1:
            print("Invalid argument to calculate n!")
            print("n must be non-negative value. But the argument was " + str(n))
            exit()
        if n < len(self.factorials):
            return self.factorials[n]
        nextArr = [0] * (n + 1 - len(self.factorials))
        initialI = len(self.factorials)
        prev = self.factorials[-1]
        m = self.MOD
        for i in range(initialI, n + 1):
            prev = nextArr[i - initialI] = prev * i % m
        self.factorials += nextArr
        return self.factorials[n]
 
    def inv(self, n):
        if n <= -1:
            print("Invalid argument to calculate n^(-1)")
            print("n must be non-negative value. But the argument was " + str(n))
            exit()
        p = self.MOD
        pi = n % p
        if pi < len(self.invModulos):
            return self.invModulos[pi]
        nextArr = [0] * (n + 1 - len(self.invModulos))
        initialI = len(self.invModulos)
        for i in range(initialI, min(p, n + 1)):
            next = -self.invModulos[p % i] * (p // i) % p
            self.invModulos.append(next)
        return self.invModulos[pi]
 
    def invFactorial(self, n):
        if n <= -1:
            print("Invalid argument to calculate (n^(-1))!")
            print("n must be non-negative value. But the argument was " + str(n))
            exit()
        if n < len(self.invFactorial_):
            return self.invFactorial_[n]
        self.inv(n)  # To make sure already calculated n^-1
        nextArr = [0] * (n + 1 - len(self.invFactorial_))
        initialI = len(self.invFactorial_)
        prev = self.invFactorial_[-1]
        p = self.MOD
        for i in range(initialI, n + 1):
            prev = nextArr[i - initialI] = (prev * self.invModulos[i % p]) % p
        self.invFactorial_ += nextArr
        return self.invFactorial_[n]
 
 
class Combination:
    def __init__(self, MOD):
        self.MOD = MOD
        self.factorial = Factorial(MOD)
 
    def ncr(self, n, k):
        if k < 0 or n < k:
            return 0
        k = min(k, n - k)
        f = self.factorial
        return f.calc(n) * f.invFactorial(max(n - k, k)) * f.invFactorial(min(k, n - k)) % self.MOD
mod=10**9+7
omod=998244353
#---------------------------------Lazy Segment Tree--------------------------------------
# https://github.com/atcoder/ac-library/blob/master/atcoder/lazysegtree.hpp
class LazySegTree:
    def __init__(self, _op, _e, _mapping, _composition, _id, v):
        def set(p, x):
            assert 0 <= p < _n
            p += _size
            for i in range(_log, 0, -1):
                _push(p >> i)
            _d[p] = x
            for i in range(1, _log + 1):
                _update(p >> i)
 
        def get(p):
            assert 0 <= p < _n
            p += _size
            for i in range(_log, 0, -1):
                _push(p >> i)
            return _d[p]
 
        def prod(l, r):
            assert 0 <= l <= r <= _n
 
            if l == r:
                return _e
 
            l += _size
            r += _size
 
            for i in range(_log, 0, -1):
                if ((l >> i) << i) != l:
                    _push(l >> i)
                if ((r >> i) << i) != r:
                    _push(r >> i)
 
            sml = _e
            smr = _e
            while l < r:
                if l & 1:
                    sml = _op(sml, _d[l])
                    l += 1
                if r & 1:
                    r -= 1
                    smr = _op(_d[r], smr)
                l >>= 1
                r >>= 1
 
            return _op(sml, smr)
 
        def apply(l, r, f):
            assert 0 <= l <= r <= _n
            if l == r:
                return
 
            l += _size
            r += _size
 
            for i in range(_log, 0, -1):
                if ((l >> i) << i) != l:
                    _push(l >> i)
                if ((r >> i) << i) != r:
                    _push((r - 1) >> i)
 
            l2 = l
            r2 = r
            while l < r:
                if l & 1:
                    _all_apply(l, f)
                    l += 1
                if r & 1:
                    r -= 1
                    _all_apply(r, f)
                l >>= 1
                r >>= 1
            l = l2
            r = r2
 
            for i in range(1, _log + 1):
                if ((l >> i) << i) != l:
                    _update(l >> i)
                if ((r >> i) << i) != r:
                    _update((r - 1) >> i)
 
        def _update(k):
            _d[k] = _op(_d[2 * k], _d[2 * k + 1])
 
        def _all_apply(k, f):
            _d[k] = _mapping(f, _d[k])
            if k < _size:
                _lz[k] = _composition(f, _lz[k])
 
        def _push(k):
            _all_apply(2 * k, _lz[k])
            _all_apply(2 * k + 1, _lz[k])
            _lz[k] = _id
 
        _n = len(v)
        _log = _n.bit_length()
        _size = 1 << _log
        _d = [_e] * (2 * _size)
        _lz = [_id] * _size
        for i in range(_n):
            _d[_size + i] = v[i]
        for i in range(_size - 1, 0, -1):
            _update(i)
 
        self.set = set
        self.get = get
        self.prod = prod
        self.apply = apply
 
 
MIL = 1 << 20
 
 
def makeNode(total, count):
    # Pack a pair into a float
    return (total * MIL) + count
 
 
def getTotal(node):
    return math.floor(node / MIL)
 
 
def getCount(node):
    return node - getTotal(node) * MIL
 
 
nodeIdentity = makeNode(0.0, 0.0)
 
 
def nodeOp(node1, node2):
    return node1 + node2
    # Equivalent to the following:
    return makeNode(
        getTotal(node1) + getTotal(node2), getCount(node1) + getCount(node2)
    )
 
 
identityMapping = -1
 
 
def mapping(tag, node):
    if tag == identityMapping:
        return node
    # If assigned, new total is the number assigned times count
    count = getCount(node)
    return makeNode(tag * count, count)
 
 
def composition(mapping1, mapping2):
    # If assigned multiple times, take first non-identity assignment
    return mapping1 if mapping1 != identityMapping else mapping2
#-------------------------------------------------------------------------
prime = [True for i in range(10)] 
pp=[0]*10
def SieveOfEratosthenes(n=10):
    p = 2
    c=0
    while (p * p <= n): 
          
        if (prime[p] == True):
            c+=1
            for i in range(p, n+1, p): 
                pp[i]+=1
                prime[i] = False
        p += 1
#---------------------------------Binary Search------------------------------------------
def binarySearch(arr, n, key):
    left = 0
    right = n-1
    mid = 0
    res=arr[n-1]
    while (left <= right):
        mid = (right + left)//2
        if (arr[mid] >= key):
            res=arr[mid]
            right = mid-1
        else:
            left = mid + 1
    return res

def binarySearch1(arr, n, key):
    left = 0
    right = n-1
    mid = 0
    res=arr[0]
    while (left <= right):
        mid = (right + left)//2
        if (arr[mid] > key):
            right = mid-1
        else:
            res=arr[mid]
            left = mid + 1
    return res
#---------------------------------running code------------------------------------------

n = int(input())
a = list(map(int, input().split()))
difficulty = a[0]
expectation = a[0] % 998244353
for i in range(1, n):
    expectation = expectation * 2 + difficulty + a[i]
    difficulty = difficulty * 2 + a[i]
    expectation %= 998244353
    difficulty %= 998244353
print(expectation)