题目描述

You are given integers $N$ and $K$. For a positive integer $k$, $f(k)$ is defined as follows.

• The sum of $\binom{N}{a_1} \times \binom{a_1}{a_2} \times \cdots \times \binom{a_{k-1}}{a_k}$ for all integer sequences $(a_1, a_2, \ldots, a_k)$ that satisfy the condition $N \ge a_1 \ge a_2 \ge \ldots \ge a_k \ge 0$.

Answer the remainder of $\sum_{k=1}^{K} f(k)$ divided by $998244353$.

For each input, solve $T$ test cases.

Note that $\binom{A}{B}$ represents "the number of ways to select $B$ distinct items from $A$ items" (i.e., the binomial coefficient).

输入格式

$$\begin{aligned} & T \\ & \text{case}_1 \\ & \vdots \\ & \text{case}_T \end{aligned} $$

Each test case is given in the following format.

$$N \quad K$$

The input satisfies the following constraints.

• All test cases consist of integers.
• $1 \le T \le 10^5$
• $0 \le N \le 10^9$
• $1 \le K \le 2 \times 10^5$
• The sum of $K$ in one test case does not exceed $2 \times 10^5$.

输出格式

Output the remainder of $\sum_{k=1}^{K} f(k)$ divided by $998244353$ for each test case.

3
3 3
0 1
31415 92653

99
1
276482222