#D2203. Converging Array (Easy Version)
Converging Array (Easy Version)
Converging Array (Easy Version)
This is the easy version of the problem. The only difference is that in this version q = 1. You can make hacks only if both versions of the problem are solved.
There is a process that takes place on arrays a and b of length n and length n-1 respectively.
The process is an infinite sequence of operations. Each operation is as follows:
- First, choose a random integer i (1 ≤ i ≤ n-1).
- Then, simultaneously set a_i = min\left(a_i, \frac{a_i+a_{i+1}-b_i}{2}\right) and a_{i+1} = max\left(a_{i+1}, \frac{a_i+a_{i+1}+b_i}{2}\right) without any rounding (so values may become non-integer).
See notes for an example of an operation.
It can be proven that array a converges, i. e. for each i there exists a limit a_i converges to. Let function F(a, b) return the value a_1 converges to after a process on a and b.
You are given array b, but not array a. However, you are given a third array c. Array a is good if it contains only integers and satisfies 0 ≤ a_i ≤ c_i for 1 ≤ i ≤ n.
Your task is to count the number of good arrays a where F(a, b) ≥ x for q values of x. Since the number of arrays can be very large, print it modulo 10^9+7.
Input
The first line contains a single integer n (2 ≤ n ≤ 100).
The second line contains n integers c_1, c_2 …, c_n (0 ≤ c_i ≤ 100).
The third line contains n-1 integers b_1, b_2, …, b_{n-1} (0 ≤ b_i ≤ 100).
The fourth line contains a single integer q (q=1).
The fifth line contains q space separated integers x_1, x_2, …, x_q (-10^5 ≤ x_i ≤ 10^5).
Output
Output q integers, where the i-th integer is the answer to the i-th query, i. e. the number of good arrays a where F(a, b) ≥ x_i modulo 10^9+7.
Example
Input
3 2 3 4 2 1 1 -1
Output
56
Note
The following explanation assumes b = [2, 1] and c=[2, 3, 4] (as in the sample).
Examples of arrays a that are not good:
- a = [3, 2, 3] is not good because a_1 > c_1;
- a = [0, -1, 3] is not good because a_2 < 0.
One possible good array a is [0, 2, 4]. We can show that no operation has any effect on this array, so F(a, b) = a_1 = 0.
Another possible good array a is [0, 1, 4]. In a single operation with i = 1, we set a_1 = min((0+1-2)/(2), 0) and a_2 = max((0+1+2)/(2), 1). So, after a single operation with i = 1, a becomes equal to [-1/2, 3/2, 4]. We can show that no operation has any effect on this array, so F(a, b) = -1/2.
inputFormat
Input
The first line contains a single integer n (2 ≤ n ≤ 100).
The second line contains n integers c_1, c_2 …, c_n (0 ≤ c_i ≤ 100).
The third line contains n-1 integers b_1, b_2, …, b_{n-1} (0 ≤ b_i ≤ 100).
The fourth line contains a single integer q (q=1).
The fifth line contains q space separated integers x_1, x_2, …, x_q (-10^5 ≤ x_i ≤ 10^5).
outputFormat
Output
Output q integers, where the i-th integer is the answer to the i-th query, i. e. the number of good arrays a where F(a, b) ≥ x_i modulo 10^9+7.
Example
Input
3 2 3 4 2 1 1 -1
Output
56
Note
The following explanation assumes b = [2, 1] and c=[2, 3, 4] (as in the sample).
Examples of arrays a that are not good:
- a = [3, 2, 3] is not good because a_1 > c_1;
- a = [0, -1, 3] is not good because a_2 < 0.
One possible good array a is [0, 2, 4]. We can show that no operation has any effect on this array, so F(a, b) = a_1 = 0.
Another possible good array a is [0, 1, 4]. In a single operation with i = 1, we set a_1 = min((0+1-2)/(2), 0) and a_2 = max((0+1+2)/(2), 1). So, after a single operation with i = 1, a becomes equal to [-1/2, 3/2, 4]. We can show that no operation has any effect on this array, so F(a, b) = -1/2.
样例
3
2 3 4
2 1
1
-1
56
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