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.*;

public class Main {
    
    static int MOD = (int) 1e9 + 7;
    
    public static void main(String[] args) throws Exception {
        
        Scanner sc = new Scanner(System.in);
        int N = sc.nextInt();
        int M = sc.nextInt();
        
        long[] dp = new long[N+1];
        int[] a = new int[M];
        for(int i = 0; i < M; i++){
            a[i] = sc.nextInt();
            dp[a[i]] = -1;
            if( (i > 0) && (a[i-1] + 1 == a[i]) ){
                System.out.println(0);
                return;
            }
        }
        
        dp[0] = 1;
        if( dp[1] != -1 ) dp[1] = 1;
        
        for(int i = 2; i <= N; i++){
            if(dp[i] == -1) continue;
            if(dp[i-2] != -1 ) dp[i] = (dp[i] + dp[i-2]) % MOD;
            if(dp[i-1] != -1 ) dp[i] = (dp[i] + dp[i-1]) % MOD;
        }
        
        System.out.println(dp[N]);
        
    }
}
