N,M=map(int,input().split())
a=[int(input()) for _ in range(M)]
mod=10**9+7
#Dynamic Programming
dp=[0]*(N+1)
dp[0]=1
if 1 not in a:
	dp[1]=1
else:
	dp[1]=0
for i in range(2,N+1):
	if i in a:
		continue
	else:
		dp[i]=dp[i-1]+dp[i-2]%mod
print(ans)