n, m = map(int, input().split())
stairs = [i for i in range(1, n+1)]
a = []
for _ in range(m):
  a.append(int(input()))

dp = [0] * (n + 1)
dp[0] = 1


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

print(dp[n] % 1000000007)