题目描述
Problem Description
Xiao S is a girl who loves counting numbers.
One day, while counting numbers in bed before sleep, she reached the number $977431$ and finally felt sleepy, deciding to go to sleep. However, she suddenly noticed that the digits of this number were in non-increasing order! She found this quite interesting and couldn't fall asleep.
She wondered how many numbers between $L$ and $R$ have digits in non-increasing order. But this problem seemed too boring.
She then thought about how many pairs $(a, b)$ between $L$ and $R$ exist such that the digits of $(a + b)$ are in non-increasing order. But this problem also seemed too boring.
Finally, she came up with a more interesting problem:
Given integers $L$, $R$, and $k$, find how many $k$-dimensional vectors $(a_1, a_2, ..., a_k)$ satisfy that the digits of $(a_1 + a_2 + ... + a_k)$ are in non-increasing order, and $\forall i \in [1, k], L \leq a_i \leq R$.
Since the answer might be very large, output it modulo $998244353$.
Input Format
The first line of input contains a positive integer $L$, as described in the problem statement.
The second line contains a positive integer $R$, as described in the problem statement.
The third line contains a positive integer $k$, as described in the problem statement.
Output Format
Output a single integer representing the number of valid vectors, modulo $998244353$.
Sample Input and Output
Sample Input #1
1
100
2
Sample Output #1
3728
Sample Input #2
19260817
1000000000
3
Sample Output #2
28745082
Sample Input #3
114514233
1919810233
10
Sample Output #3
135934411
Sample Input #4
See attached file digit4.in
Sample Output #4
See attached file digit4.ans
Sample Input #5
See attached file digit5.in
Sample Output #5
See attached file digit5.ans
Notes/Hints
[Data Range and Constraints]
For all data, $1 \leq L \leq R < 10^{1000}$, $1 \leq k \leq 50$.
The specific data range and constraints are as follows:
| Test Case Number | $R <$ | $k$ |
|---|---|---|
| 1 | $10^6$ | 1 |
| 2 | $10^6$ | 10 |
| 3 | $10^6$ | 20 |
| 4 | $10^6$ | 30 |
| 5 | $10^6$ | 50 |
| 6 | $10^{17}$ | 10 |
| 7 | $10^{17}$ | 10 |
| 8 | $10^{17}$ | 20 |
| 9 | $10^{17}$ | 30 |
| 10 | $10^{17}$ | 50 |
| 11 | $10^{50}$ | 2 |
| 12 | $10^{50}$ | 10 |
| 13 | $10^{100}$ | 2 |
| 14 | $10^{100}$ | 3 |
| 15 | $10^{100}$ | 10 |
| 16 | $10^{200}$ | 3 |
| 17 | $10^{200}$ | 10 |
| 18 | $10^{300}$ | 10 |
| 19 | $10^{300}$ | 10 |
| 20 | $10^{300}$ | 20 |
| 21 | $10^{500}$ | 10 |
| 22 | $10^{500}$ | 20 |
| 23 | $10^{1000}$ | 30 |
| 24 | $10^{1000}$ | 50 |
| 25 | $10^{1000}$ | 50 |
输入格式
见题面 Input 部分
输出格式
见题面 Output 部分