import java.util.Scanner;

public class Main {

	static final int MOD = 1000000007;

	public static void main(String[] args) {

		Scanner sc = new Scanner(System.in);
		int N = Integer.parseInt(sc.next());
		int M = Integer.parseInt(sc.next());
		boolean[] a = new boolean[N + 1];
		for (int i = 0; i < M; i++) {
			a[Integer.parseInt(sc.next())] = true;
		}
		sc.close();

		long[] ans = new long[N + 1];
		ans[0] = 1;
		ans[1] = a[1] ? 0 : 1;
		for (int i = 2; i <= N; i++) {
			if (a[i]) {
				ans[i] = 0;
			} else {
				ans[i] = getMod(ans[i - 1] + ans[i - 2]);
			}
		}
		System.out.println(getMod(ans[N]));

	}

	static long getMod(long a) {
		return a >= 0 ? a % MOD : MOD + a % MOD;
	}

}