n,m,*a=map(int,open(0).read().split())
dp=[0]*(n+2)
dp[0]=1
div=1000000007
for i in range(n):
  dp[i]%=div
  if i+1 in a:
    dp[i+1]=0
  else:
    dp[i+1]+=dp[i]
  if i+2 in a:
    dp[i+2]=0
  else:
    dp[i+2]+=dp[i]
print(dp[n]%div)