n,m = map(int, input().split())
div = 1000000007
ok [True] * n
for _ in range(m):
  a = int(input())
  ok[a] = False
dp = [0] * (n + 1)
dp[0] = 1
if ok[1]:
  dp[1] = 1
else:
  dp[1] = 0

for i in range(2, n+1):
  if ok[i]:
    dp[i] = dp[i-1] + dp[i-2]
    dp[i] %= div

print(dp[n])
  