题目描述
Problem Statement
You are given integers R, G, B, and K. How many strings S consisting of R, G, and B satisfy all of the conditions below? Find the count modulo 998244353.
- The number of occurrences of R, G, and B in S are R, G, and B, respectively.
- The number of occurrences of RG as (contiguous) substrings in S is K.
Input
Input is given from Standard Input in the following format:
R G B K
Output
Print the answer.
Constraints
- $1 \leq R,G,B\leq 10^6$
- $0 \leq K \leq \mathrm{min}(R,G)$
- All values in input are integers.
Sample Input 1
2 1 1 1
Sample Output 1
6
The following six strings satisfy the conditions.
- RRGB
- RGRB
- RGBR
- RBRG
- BRRG
- BRGR
Sample Input 2
1000000 1000000 1000000 1000000
Sample Output 2
80957240
Find the count modulo 998244353.
输入格式
见题面 Input 部分
输出格式
见题面 Output 部分
样例输入
2 1 1 1
样例输出
6