n, m = map(int, input().split())
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:
    dp[i] = 0
    continue
  dp[i] = dp[i-1] + dp[i-2]

mod = 1000000007
print(dp[-1]%mod)