n, m = map(int, input().split())
a = [int(input()) for i in range(m)]
dp = [0] * (n+1)
dp[0] = 1
if 1 not in a:
  dp[1] = 1
for i in range(2, n+1):
  if i in a:
    continue
  dp[i] = dp[i-1] + dp[i-2]
print(dp[-1]%(10 ** 9 + 7))