N,M = map(int,input().split())
a = set([int(input()) for _ in range(M)])
mod = 10**9+7
dp=[0]*(N+1)
dp[1]=1


for i in range(N):
  if i+1 not in a:
    dp[i+1]+=dp[i]
    dp[i+1] %= mod
  if i+2 <= N and i+2 not in a:
    dp[i+2]+=dp[i]
    dp[i+2]%=mod
  
print(dp[-1])
