N, M = map(int, input().split())
A = [int(input()) for _ in range(M)]
A = set(A)

mod = 1000000007

dp = [0] * (N + 1)

if len(dp) <= 2:
  return 1

dp[-1] = 1
dp[-2] = 1 if N - 1 not in A else 0

for i in range(N-2, -1, -1):
  if i not in A:
    dp[i] = dp[i+1] + dp[i+2]

print(dp[0] % mod)
