n,m=map(int,input().split())
a=[int(input())for _ in range(m)]
mod=10**9+7
if n==1:
	print(1)
	exit()
dp = [0]*(n+1)
dp[0]=1
dp[1]=1 if a[0]!=1 else 0

for i in range(2,n+1):
	if i in a:
		continue
	dp[i] = dp[i-2]+dp[i-1]
	dp[i]%=mod
print(dp[n])
