N,M=map(int,input().split())
A={int(input()) for _ in range(M)}
mod=10**9+7

dp=[0]*(N+1)
dp[0]=1
dp[1]=1
if 1 in A:
  dp[1]=0

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