N,M = (int(i) for i in input().split()) 
a = [int(input()) for i in range(M)] 

mod=10**9+7

dp=[0]*(N+1)

dp[0]=1
if 1 in a:
	dp[1]=0
else:
	dp[1]=1

for i in range(0, N-1):
	if i+2 in a:
		dp[i+2]=0
	else:
		dp[i+2]+=dp[i+1]+dp[i]
	
print(dp[N]%mod)