After defeating Little L in the third game, General Jump allowed you to leave Jump Castle.
Following a long siege of Jump Castle, the Flea King ordered his troops to launch an all-out attack. The battle was fierce, and you made a significant contribution by using the map you obtained while infiltrating the castle to discover a breakthrough—a small, unguarded gate. A tide of fleas and crickets poured through, and the flea-cricket coalition finally succeeded in recapturing Jump Castle, restoring the Flea Kingdom.
At the victory banquet, the flea band played a newly composed song, "You Will Return Like Lightning." The Flea King was in high spirits and posed a problem to the guests, promising a grand reward to anyone who could solve it:
Given a labeled rooted tree where each node is colored either red or green, we call it a "Lightning Tree" if and only if:
- The parent $p_i$ of each node $i$ satisfies $p_i < i$.
- Each level of the tree contains exactly one red node.
- For any node that is not the root, its parent must be red.
- Every red node has an even number of green children.
"It can be deduced that the red nodes in a Lightning Tree form a red path from the root down to some leaf node, like a red lightning bolt cutting through the obstacles ahead..." the Flea King described vividly.
Given $k$ and $n$, find the number of Lightning Trees with $n$ nodes and $k$ levels, modulo $998244353$.
This problem is very difficult, and the other guests were at a loss, but you—Volt, a computer expert—realized that this problem could be easily solved with a computer. Once you solve it, the grand reward is yours!
Input
A single line containing two positive integers $k$ and $n$, representing the number of levels and the number of nodes in the tree, respectively.
Output
A single integer representing the answer modulo $998244353$.
Examples
Input 1
2 10
Output 1
9
Note 1
It is easy to see that the tree structure must satisfy $p_2=p_3=\ldots=p_{10}=1$, meaning the first level is node $1$, and the second level consists of nodes $2$ through $10$.
Regarding the colors, node $1$ must be red, and exactly one of nodes $2$ through $10$ must be red, with the rest being green. Thus, there are $9$ possible configurations.
Input 2
3 7
Output 2
65
Input 3
8 14
Output 3
703179
Input 4
529 1453
Output 4
159030840
Input 5
1453 14530529
Output 5
443513052
Input 6
10 1000000000000000000
Output 6
384797525
Constraints
For all test cases, $1\le k\le 10^7$, $k\le n\le 10^{18}$, and $k\equiv n \pmod 2$.
| Subtask | $k\le$ | $n\le$ | Score |
|---|---|---|---|
| $1$ | $n$ | $100$ | $15$ |
| $2$ | $3\times 10^3$ | $10$ | |
| $3$ | $10^5$ | $15$ | |
| $4$ | $10^7$ | $10$ | |
| $5$ | $3$ | $10^{18}$ | $5$ |
| $6$ | $100$ | $15$ | |
| $7$ | $10^3$ | $15$ | |
| $8$ | $10^7$ | $15$ |