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

dp=[0]*(n+1)
for i in range(n,-1,-1):
  if i in a:
    dp[i] = 0
  elif i==n:
    dp[i]=1
  elif i==n-1:
    dp[i]=1
  else:
    dp[i]=dp[i+1]+dp[i+2]
    dp[i]=dp[i]%1000000007
print(dp[0])