Problem Statement

Given are a sequence of $N integers A_1, A_2, \ldots, A_N$ and a positive integer S.
For a pair of integers (L, R) such that $1\leq L \leq R \leq N$, let us define f(L, R) as follows:

• f(L, R) is the number of sequences of integers $(x_1, x_2, \ldots , x_k)$ such that $L \leq x_1 < x_2 < \cdots < x_k \leq R$ and $A_{x_1}+A_{x_2}+\cdots +A_{x_k} = S$.

Find the sum of f(L, R) over all pairs of integers (L, R) such that $1\leq L \leq R\leq N.$ Since this sum can be enormous, print it modulo 998244353.

Input

Input is given from Standard Input in the following format:
N S
A_1 A_2 ... A_N

Output

Print the sum of f(L, R), modulo 998244353.

Constraints

• All values in input are integers.
• $1 \leq N \leq 3000$
• $1 \leq S \leq 3000$
• $1 \leq A_i \leq 3000$

Sample Input 1

3 4
2 2 4

Sample Output 1

5

The value of f(L, R) for each pair is as follows, for a total of 5.

• f(1,1) = 0
• f(1,2) = 1 (for the sequence (1, 2))
• f(1,3) = 2 (for (1, 2) and (3))
• f(2,2) = 0
• f(2,3) = 1 (for (3))
• f(3,3) = 1 (for (3))

Sample Input 2

5 8
9 9 9 9 9

Sample Output 2

0

Sample Input 3

10 10
3 1 4 1 5 9 2 6 5 3

Sample Output 3

152

见题面 Input 部分

见题面 Output 部分