题目描述
For a finite multiset $S$ of non-negative integers, let us define $\mathrm{mex}(S)$ as the smallest non-negative integer not in $S$. For instance, $\mathrm{mex}(\lbrace 0,0, 1,3\rbrace ) = 2, \mathrm{mex}(\lbrace 1 \rbrace) = 0, \mathrm{mex}(\lbrace \rbrace) = 0$.
There are $N$ non-negative integers on a blackboard. The $i$\-th integer is $A_i$.
You will perform the following operation exactly $K$ times.
- Choose zero or more integers on the blackboard. Let $S$ be the multiset of chosen integers, and write $\mathrm{mex}(S)$ on the blackboard once.
How many multisets can be the multiset of integers on the final blackboard? Find this count modulo $998244353$.
输入格式
The input is given from Standard Input in the following format:
>$N$ $K$
$A_1$ $A_2$ $\ldots$ $A_N$
#### Constraints
- $1 \leq N,K \leq 2\times 10^5$
- $0\leq A_i\leq 2\times 10^5$
- All numbers in the input are integers.