题目描述
Problem Statement
There is a set consisting of N distinct integers. The i-th smallest element in this set is S_i. We want to divide this set into two sets, X and Y, such that:
- The absolute difference of any two distinct elements in X is A or greater.
- The absolute difference of any two distinct elements in Y is B or greater.
How many ways are there to perform such division, modulo 10^9 + 7? Note that one of X and Y may be empty.
Input
The input is given from Standard Input in the following format:
N A B
S_1
:
S_N
Output
Print the number of the different divisions under the conditions, modulo 10^9 + 7.
Constraints
- All input values are integers.
- 1 ≦ N ≦ 10^5
- 1 ≦ A , B ≦ 10^{18}
- 0 ≦ S_i ≦ 10^{18}(1 ≦ i ≦ N)
- S_i < S_{i+1}(1 ≦ i ≦ N - 1)
Sample Input 1
5 3 7
1
3
6
9
12
Sample Output 1
5
There are five ways to perform division:
- X={1,6,9,12}, Y={3}
- X={1,6,9}, Y={3,12}
- X={3,6,9,12}, Y={1}
- X={3,6,9}, Y={1,12}
- X={3,6,12}, Y={1,9}
Sample Input 2
7 5 3
0
2
4
7
8
11
15
Sample Output 2
4
Sample Input 3
8 2 9
3
4
5
13
15
22
26
32
Sample Output 3
13
Sample Input 4
3 3 4
5
6
7
Sample Output 4
0
输入格式
见题面 Input 部分
输出格式
见题面 Output 部分