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.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n = Integer.parseInt(sc.next());//int型
        int m = Integer.parseInt(sc.next());
        int[] a = new int[m];
        int[] dp = new int[n+1]; // i段目に行く場合の数

        for (int i = 0; i < m; i++) {
            a[i] = Integer.parseInt(sc.next());
        }
        sc.close();

        boolean[] check = new boolean[n+1];
        for (int i = 0; i < m; i++) {
            check[a[i]] = true;
        }

        // 0段目には1通り
        // 1段目には1通り
        dp[0] = 1;
        if(!check[1]) dp[1] = 1;
        else dp[1] = 0;
        for (int i = 0; i <= n-2; i++) {
            if(!check[i+2]) dp[i+2] = (dp[i+1] + dp[i]) % 1000000007;
            else dp[i+2] = 0;
        }
/*
        for (int i = 0; i < n+1; i++) {
            System.out.println(dp[i]);
        }
*/
        System.out.println(dp[n]);
    }
}
