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