Problem9161--ABC281 —— Ex - Alchemy

9161: ABC281 —— Ex - Alchemy

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Time Limit : 5.000 sec  Memory Limit : 512 MiB

Description

Takahashi has $A$ kinds of level-$1$ gems, and $10^{10^{100}}$ gems of each of those kinds.  
For an integer $n$ greater than or equal to $2$, he can put $n$ gems that satisfy all of the following conditions into a cauldron to generate a level-$n$ gem in return.

-   No two gems are of the same kind.
-   Every gem's level is less than $n$.
-   For every integer $x$ greater than or equal to $2$, there is at most one level-$x$ gem.

Find the number of kinds of level-$N$ gems that Takahashi can obtain, modulo $998244353$.

Here, two level-$2$ or higher gems are considered to be of the same kind if and only if they are generated from the same set of gems.

-   Two sets of gems are distinguished if and only if there is a gem in one of those sets such that the other set does not contain a gem of the same kind.

Any level-$1$ gem and any level-$2$ or higher gem are of different kinds.

Input

The input is given from Standard Input in the following format:

```
$N$ $A$
```

Output

Print the answer.

Constraints

-   $1 \leq N \leq 2 \times 10^5$
-   $1 \leq A \leq 10^9$
-   $N$ and $A$ are integers.

Sample 1 Input

3 3

Sample 1 Output

10
Here are ten ways to obtain a level-3 gem.
  • Put three kinds of level-1 gems into the cauldron.
    • Takahashi has three kinds of level-1 gems, so there is one way to choose three kinds of level-1 gems. Thus, he can obtain one kind of level-3 gem in this way.
  • Put one kind of level-2 gem and two kinds of level-1 gems into the cauldron.
    • A level-2 gem can be obtained by putting two kinds of level-1 gems into the cauldron.
      • Takahashi has three kinds of level-1 gems, so there are three ways to choose two kinds of level-1 gems. Thus, three kinds of level-2 gems are available here.
    • There are three kinds of level-2 gems, and three ways to choose two kinds of level-1 gems, so he can obtain 3×3=9 kinds of level-3 gems in this way.

Sample 2 Input

1 100

Sample 2 Output

100

Sample 3 Input

200000 1000000000

Sample 3 Output

797585162

HINT

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