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