N,M=map(int,input().split())
a=[int(input()) for i in range(M)]
dp=[0]*(N+1)
dp[0]=1
anlist=[]
inf=10**9+7
if 1 not in a:
  dp[1]=1
else:
  dp[1]=0
for i in range(2,N+1):
  if i in a:
    continue
  else:
    dp[i]=dp[i-1]+dp[i-2]
for i in dp:
  i=i%inf
  anlist.append(i)
ans=anlist[N]%inf
print(ans)

  