import java.util.*;


public class Main {
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		
		int n = sc.nextInt();
		int m = sc.nextInt();
		int a[] = new int[n+1];
		for(int i = 0; i < m; i++){
		    a[sc.nextInt()] = 1;
    }
    
		long result = 0;
		long[] dp = new long[n+1];
		for(int i = 1; i < n+1; i++){
		    if(a[i] == 1) dp[i] = 0;
            else if(i == 1)dp[i] = 1;
            else if(i == 2)
                dp[i] = 1;
            else{
            dp[i] = dp[i-1] + dp[i-2];
            dp[i]%=1000000007;
		    }
    }
		System.out.println(dp[n]);
		
	}
}
