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.util.Arrays;
import java.util.StringTokenizer;

public class Main
{
    static long[] dp;
    static int N,M;
    static final int MOD = 1000000007;
    public static void main(String[] args) throws IOException
    {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(System.out));
        StringTokenizer st = new StringTokenizer(br.readLine());
        N = Integer.parseInt(st.nextToken());
        M = Integer.parseInt(st.nextToken());
        dp = new long[N+1];
        Arrays.fill(dp,-1);
        dp[0] = 1; dp[1] = 1;
        for(int i=0;i<M;++i)
        {
            dp[Integer.parseInt(br.readLine())] = 0;
        }
        for(int i=0;i<=N;++i)
        {
            if(dp[i]!=-1) continue;
            dp[i] = (dp[i-1]+dp[i-2])%MOD;
        }
        bw.write(dp[N]+"");
        bw.close();
    }

}
