n,m=map(int,input().split())
a=set()
for i in range(m):
  a.add(int(input()))
mod=10**9+7
dp=[0]*(n+1)
dp[0]=1
if 1 in a:
  dp[1]=0
else:
  dp[1]=1
if 2 in a:
  dp[2]=0
else:
  dp[2]=dp[1]+1
for i in range(3,n+1):
  if i in a:
    dp[i]=0
  else:
    dp[i]=(dp[i-1]+dp[i-2])%mod
print(dp[n])