n,m=map(int,input().split())
broken=[False]*(n+1)
for i in range(m):
  broken[int(input())]=True
dp=[0]*(n+1)
dp[0]=1
dp[1]=1 if 1 not in broken else 0

for i in range(2,len(dp)):
  if broken[i]:
    dp[i]=0
  else:
    dp[i]=(dp[i-2]+dp[i-1])%1000000007
  
print(dp[-1])
