n, m = map(int, input().split())
ls = [int(input()) for _ in range(m)]

dp = [0] * (n + 1)
dp[0] = 1

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

ls.append(0)

for i in range(2, n + 1):
	if i == ls[0]:
		dp[i] == 0
		del ls[0]
	else:
		dp[i] = dp[i - 1] + dp[i - 2]
		
print(dp[n] % 1000000007)