def solve():
	N, M = map(int, input().split())
	A = [int(input()) for _ in range(M)]

	dp = [0]*(N+1)
	dp[0] = 1
	if 1 in A:
		dp[1] = 0
	else:
		dp[1] = 1

	for i in range(2, N+1):
		if i in A:
			dp[i] = 0
		else:
			dp[i] = dp[i-1] + dp[i-2]

	print(dp[N]%1000000007)

solve()
