N, M = map(int, input().split())
a_list = set([int(input()) for i in range(M)])
dp = [0]*(N+1)

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])