n, m = map(int, input().split())
a = [int(input()) for _ in range(m)]

mod = 10**9+7
dp = [0]*(n+1)
dp[0]=1

if not 1 in a:
  dp[1]=1

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

print(dp[n]%mod)
