n,m=map(int,input().split())
a=[int(input()) for i in range(m)]
dp=[0]*(n+1)
dp[0]=0
if n>2:
  if 1 in a:
    dp[1]=0
    dp[2]=1
  else:
    dp[1]=1
    dp[2]=2
  for i in range(3,n+1):
    if i in a:
      dp[i]=0
    else:
      dp[i]=dp[i-1]+dp[i-2]
  print(dp[n]%1000000007)
else:
  if m==0:
    print(1)
  else:
    print(0)