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 1 not in a:
  dp[1]=1
else:
  dp[1]=0
  

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

