mod = 1000000007

n, m = list(map(int, input().split()))
nums = [int(input()) for _ in range(m)]
 
dp = [1] + [0 for _ in range(n)]

if nums[0] == 1:
	del nums[0]
else:
	dp[1] = 1
	

for i in range(2, n + 1):
	#print(i, dp, nums)
	if len(nums) ==  0:
		dp[i] = (dp[i - 1] + dp[i - 2]) % mod
	else:
		for j in range(len(nums)):
			if nums[j] > i:
				dp[i] = (dp[i - 1] + dp[i - 2]) % mod
				break
			elif nums[j] == i:
				del nums[:(j + 1)]
				break
#print(nums)
#print(dp)
print(dp[-1])
