n,m = map(int,input().split())
As = [int(input()) for _ in range(m)]
dp = [0]*n
dp[0] = 1 if 1 not in As else 0
dp[1] = ( 1 if 1 in As else  2  )if 2 not in As else 0
for i in range(2,n):
  if i+1 not in As:
    dp[i] = dp[i-1]+dp[i-2]
  else:
    dp[i] = 0
print(dp[n-1]%((10**9)+7))