N, M = map(int, input().split())
a = [int(input()) for i in range(M)]
dp = [0] * (N+1)
for i in range(N+1):
  if i in a:
    dp[i] = 0
  elif i <= 1:
    dp[i] = 1
  else:
    dp[i] = (dp[i-1] + dp[i-2]) % (10**9+7)
print(dp[N])