P25094 [AtCoder] Products of Min
普及
题目描述

Problem Statement

Given is a sequence A of N integers. There are 2^N - 1 non-empty subsequences B of A. Find the sum of $\max\left(B\right) \times \min\left(B\right)$ over all of them.
Since the answer can be enormous, report it modulo 998244353.

Input

Input is given from Standard Input in the following format:
N
$A_1 A_2 \cdots A_N$

Output

Print the answer.

Constraints

  • All values in input are integers.
  • $1 \leq N \leq 2 \times 10^5$
  • $0 \leq A_i \leq 998244352$

Sample Input 1

3
2 4 3

Sample Output 1

63

There are 7 subsequences B, as follows:

  • $B = \left(2\right)$ : $\max\left(B\right) \times \min\left(B\right) = 4$
  • $B = \left(4\right)$ : $\max\left(B\right) \times \min\left(B\right) = 16$
  • $B = \left(3\right)$ : $\max\left(B\right) \times \min\left(B\right) = 9$
  • $B = \left(2, 4\right)$ : $\max\left(B\right) \times \min\left(B\right) = 8$
  • $B = \left(2, 3\right)$ : $\max\left(B\right) \times \min\left(B\right) = 6$
  • $B = \left(4, 3\right)$ : $\max\left(B\right) \times \min\left(B\right) = 12$
  • $B = \left(2, 4, 3\right)$ : $\max\left(B\right) \times \min\left(B\right) = 8$

The answer is the sum of them: 63.

Sample Input 2

1
10

Sample Output 2

100

Sample Input 3

7
853983 14095 543053 143209 4324 524361 45154

Sample Output 3

206521341

输入格式

见题面 Input 部分

输出格式

见题面 Output 部分

样例输入
3 2 4 3
样例输出
63