n,m=map(int,input().split())
a=[int(input()) for i in range(m)]
dp=[-1]*(n+1)
dp[0]=1
dp[1]=1
for i in range(2,n+1):
    if i in a:
        dp[i]=0
        continue
    dp[i]=dp[i-1]+dp[i-2]
print(dp[-1]%(10**9+7))