n,m=map(int,input().split())
lst=[int(input()) for i in range(m)]
DP=[0]*(n+1)
temp=0
DP[0]=1
DP[1]=1
for i in range(n+1):
  if i in lst:
    DP[i]=0
  else:
    DP[i]=(DP[i-1]+DP[i-2])%(10**9+7)
print(DP[n])