Problem: Problem statement

N-winged rabbit is on a balance beam of length L-1. The initial position of the i-th rabbit is the integer x_i, which satisfies 0 ≤ x_ {i} \ lt x_ {i + 1} ≤ L−1. The coordinates increase as you move to the right. Any i-th rabbit can jump to the right (ie, move from x_i to x_i + a_i) any number of times, just a distance a_i. However, you cannot jump over another rabbit or enter a position below -1 or above L. Also, at most one rabbit can jump at the same time, and at most one rabbit can exist at a certain coordinate.

How many possible states of x_ {0},…, x_ {N−1} after starting from the initial state and repeating the jump any number of times? Find by the remainder divided by 1 \, 000 \, 000 \, 007.

input

The input is given in the following format.


N L
x_ {0}… x_ {N−1}
a_ {0}… a_ {N−1}


Constraint

* All inputs are integers
* 1 \ ≤ N \ ≤ 5 \,000
* N \ ≤ L \ ≤ 5 \,000
* 0 \ ≤ x_ {i} \ lt x_ {i + 1} \ ≤ L−1
* 0 \ ≤ a_ {i} \ ≤ L−1



output

Print the answer in one line.

sample

Sample input 1


13
0
1


Sample output 1


3


If 1/0 is used to express the presence / absence of a rabbit, there are three ways: 100, 010, and 001.

Sample input 2


twenty four
0 1
1 2


Sample output 2


Four


There are four ways: 1100, 1001, 0101, 0011.

Sample input 3


10 50
0 1 2 3 4 5 6 7 8 9
1 1 1 1 1 1 1 1 1 1


Sample output 3


272278100


The binomial coefficient C (50,10) = 10 \, 272 \, 278 \, 170, and the remainder obtained by dividing it by 1 \, 000 \, 000 \, 007 is 272 \, 278 \, 100.





Example

Input

1 3
0
1


Output

3

Solution (in CPP):

Solution:
#include <stdio.h>
int N, L, ret, x[5000], a[5000], dp[5001][5001];
int main() {
	scanf("%d%d", &N, &L);
	for (int i = 0; i < N; i++) scanf("%d", &x[i]);
	for (int i = 0; i < N; i++) scanf("%d", &a[i]), a[i] = a[i] ? a[i] : L;
	dp[N][L] = 1;
	for (int i = N - 1; i >= 0; i--) {
		int sum = dp[i + 1][L];
		for (int j = L - 1; j >= 0; j--) {
			if (j >= x[i] && (j - x[i]) % a[i] == 0) {
				dp[i][j] = sum;
			}
			sum = (sum + dp[i + 1][j]) % 1000000007;
		}
	}
	for (int i = 0; i < L; i++) ret = (ret + dp[0][i]) % 1000000007;
	printf("%d\n", ret);
	return 0;
}