N, M = map(int, input().split())
a = [int(input()) for i in range(M)]

#動的計画法問題
dp = [0] * (N+1)
dp[0] = 1
if 1 not in a:
  dp[1] = 1
  else:
    dp[1] = 0

    for i in range(2,N+1):
      if i in a:
        continue
        dp[i] = dp[i-1] + dp[i-2]

        dp[i] %= (10**9+7)

print(dp[N]) 
