题目描述
Problem Description
Little W is currently learning a certain programming language.
This programming language has a statement as follows:
range(a,b,c)
This statement represents a sequence, which is defined as:
$$ [a, a+c, a+2c, \cdots, a+kc] $$
where $k$ is the largest non-negative integer such that $a+kc < b$. For example, range(1,7,2) represents the sequence $[1,3,5]$.
Little W wants to ask you a question: Given a sequence $g$ of length $n$ (indexed from 1), compute the value of the following expression, modulo $10^9 + 7$.
$$ \sum_{a=1}^{n}\sum_{b=a+1}^{n+1}\sum_{c=1}^{n}\sum_{i \in \mathrm{range}(a,b,c)} g_i $$
Input Format
To speed up the input, we use the following method.
The input consists of one line with five non-negative integers $n, A, B, C, g_n$.
Here, $n$ is the length of the sequence $g$, and $A, B, C$ are parameters for generating the data, with $g_n$ being the $n$-th element of the sequence $g$.
For the $i$-th element of the sequence $g$ (where $1 \leq i < n$), it satisfies $g_i \equiv A g_{i+1}^2 + B g_{i+1} + C \pmod{10^9 + 7}$.
Output Format
Output a single non-negative integer, which is the answer to the problem.
Sample Input and Output
Sample Input #1
2 0 1 1 1
Sample Output #1
11
Sample Input #2
9 0 1 0 663
Sample Output #2
422994
Sample Input #3
20 1 0 0 998244353
Sample Output #3
560706529
Sample Input #4
114514 17723 134 1045 233337
Sample Output #4
442762986
Notes
Sample Explanation #1
$g = [2, 1]$ (indexed from 1)
Let $= \sum_{i \in \mathrm{range}(a,b,c)} g_i$.
When $a=1, b=2, c=1$, $ans = 2$.
When $a=1, b=2, c=2$, $ans = 2$.
When $a=1, b=3, c=1$, $ans = 2 + 1 = 3$.
When $a=1, b=3, c=2$, $ans = 2$.
When $a=2, b=3, c=1$, $ans = 1$.
When $a=2, b=3, c=2$, $ans = 1$.
The answer is $\sum ans = 2 + 2 + 3 + 2 + 1 + 1 = 11$.
Sample Explanation #2
This sample satisfies special property A.
Data Range
For $100\%$ of the data: $1 \leq n \leq 2 \times 10^7$, $0 \leq A, B, C, g_n < 10^9 + 7$.
| Test Case Number | $n =$ | Special Property |
|---|---|---|
| 1 | 1 | AB |
| 2 | 1000 | None |
| 3 | 1000 | None |
| 4 | 5000 | None |
| 5 | 5000 | None |
| 6 | 10^4 | A |
| 7 | 10^5 | A |
| 8 | 10^5 | B |
| 9 | 10^5 | None |
| 10 | $2 \times 10^5$ | A |
| 11 | $2 \times 10^5$ | B |
| 12 | $5 \times 10^5$ | None |
| 13 | 10^6 | A |
| 14 | 10^6 | B |
| 15 | $2 \times 10^6$ | None |
| 16 | $3 \times 10^6$ | None |
| 17 | $5 \times 10^6$ | A |
| 18 | 10^7 | A |
| 19 | 10^7 | B |
| 20 | 1.$3 \times 10^7$ | None |
| 21 | 1.$6 \times 10^7$ | None |
| 22 | $2 \times 10^7$ | A |
| 23 | $2 \times 10^7$ | B |
| 24 | $2 \times 10^7$ | None |
| 25 | $2 \times 10^7$ | None |
Special Property A: All $g_i$ are equal.
Special Property B: Only $g_n \neq 0$.
输入格式
见题面 Input 部分
输出格式
见题面 Output 部分