n,m=map(int,input().split())
mod=10**9+7
t=[int(input()) for i in range(m)] 
dp=[-1]*(n+1)

dp[0]=0
dp[1]=1
dp[2]=1

for i in range(m):
    dp[t[i]]=0

for i in range(3,n+1):
    if dp[i]==-1:
        dp[i]=dp[i-1]+dp[i-2]
print(dp[-1]%mod)
