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

dp=[0]*(n+1)

dp[0]=1

if 1 in a:
  dp[1]=0
else:
  dp[1]=1
  

for i in range(2,n+1):
  if i in a:
    dp[i]=0
  else:
    dp[i]=(dp[i-1]+dp[i-2])%(10**9+7)
    
print(dp[n])