n,m = map(int,input().split())
a = [int(input()) for i in range(m)]
mod = 10**9+7
dp = [0]*(n+1)
dp[0] = 1
j=0
for i in range(1,n+1):
  if j in a:
    #dp[a[j]] = 0 
    continue
  if i==1:
    dp[1] = dp[0]
    continue
  dp[i] = dp[i-1]+dp[i-2]
  dp[i]%=mod
print(dp[n])