N, M = map(int, input().split())
a_list = []
dp = [0]*(N+1)
for _ in range(M):
  a = int(input())
  a_list.append(a)

dp[0] = 1
for i in range(1,N+1):
  dp[i] = (dp[i-1] + dp[i-2])%(10**9+7)
  if i in a_list:
    dp[i] = 0
print(dp[N])