n,m=map(int,input().split())
a=[int(input()) for i in range(m)]
MOD=1000000007

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