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 {
	public static void main(String[] args) {
		Main main = new Main();
		main.run();
	}

	public void run() {
		Scanner sc = new Scanner(System.in);
		int N=sc.nextInt();
		int M=sc.nextInt();
		ArrayList<Integer> a = new ArrayList<Integer>();
		for(int i=0; i<M; i++) {
			a.add(sc.nextInt());
		}

		int MOD = 1000000007;
		long dp[] = new long[N+1];
		dp[0] = 1;
		int j=0;
		for(int i=1; i<=N; i++) {
			if(j<M && a.get(j) == i) {
				j++;
				continue;
			}
			dp[i] += dp[i-1];
			dp[i] %= MOD;
			if(i-2>=0) {
				dp[i] += dp[i-2];
				dp[i] %= MOD;
			}
		}
		System.out.println(dp[N]);
		sc.close();
	}
}
