There is a staircase with N steps. Takahashi is now standing at the foot of the stairs, that is, on the 0-th step. He can climb up one or two steps at a time.

However, the treads of the a_1-th, a_2-th, a_3-th, \ldots, a_M-th steps are broken, so it is dangerous to set foot on those steps.

How many are there to climb up to the top step, that is, the N-th step, without setting foot on the broken steps? Find the count modulo 1\ 000\ 000\ 007.

Constraints

* 1 \leq N \leq 10^5
* 0 \leq M \leq N-1
* 1 \leq a_1 < a_2 < ... < a_M \leq N-1

Input

Input is given from Standard Input in the following format:


N M
a_1
a_2
.
.
.
a_M


Output

Print the number of ways to climb up the stairs under the condition, modulo 1\ 000\ 000\ 007.

Examples

Input

6 1
3


Output

4


Input

10 2
4
5


Output

0


Input

100 5
1
23
45
67
89


Output

608200469
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.util.*;
public class Main { //atcoder ABC128C -

	public static void main(String[] args) throws Exception {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		StringTokenizer st = new StringTokenizer(br.readLine());
		int n = Integer.parseInt(st.nextToken());
		int m = Integer.parseInt(st.nextToken());
		boolean[] arr = new boolean[n+1];
		long[] count = new long[n+1];
		for(int i = 0; i < m; i++){
			int a = Integer.parseInt(br.readLine());
			arr[a] = true;
		}
		count[0] = 1;
		count[1] = arr[1] ? 0 : 1;
		for(int i = 2; i <= n; i++){
			if(!arr[i]) {
				count[i] = (count[i-1] + count[i-2]) % 1000000007;
			}
		}
		System.out.println(count[n]);
	}
}
