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.*;
import java.math.*;
import java.util.*;
public class Main {

	public static void main(String[] args) { //Boolean markers+DP
		Scanner input = new Scanner(System.in);
		int N = input.nextInt();
		int M = input.nextInt();
		boolean[] bad = new boolean[N+1];
		long mod = (long)(1e9+7);
		long[] dp = new long[N+1];
		for (int i = 0; i < M; i++) {
			int x = input.nextInt();
			bad[x]=true;
		}
		if (N==1) System.out.println(1);
		else {
			if (!bad[1]) dp[1]=1;
			if (!bad[2]) dp[2]=dp[1]+1;
			for (int step = 3; step<=N; step++) {
				if (!bad[step]) {
					dp[step]=dp[step-1]+dp[step-2];
					dp[step]%=mod;
				} 
			}
			System.out.println(dp[N]);
		}	
	}	
}