n, m = map(int, input().split())
mod = 1000000007

a = [True] * (n + 1)
for i in range(m):
    a[int(input())] = False
dp = [0] * (n + 1)
dp[0] = 1
dp[1] = dp[0] if not 1 in a else 0
for i in range(2, n + 1):
  if a[i]:
      dp[i] = (dp[i - 1] + dp[i - 2]) % mod
  else:
      dp[i]=  0
print(dp(n))
