N,M=[int(i) for i in input().split()]
inf=1000000007
aa=[]
for i in range(M):
	aa.append(int(input()))
dp=[0]*(N+1)
dp[0]=1
if 1 in aa:
	dp[1]=0
else:
	dp[1]=1
for i in range(2,N+1):
	if i in aa:
		dp[i]=0
	else:
		dp[i]=dp[i-2]%inf+dp[i-1]%inf
print(dp[N]%inf)