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