n,m=map(int,input().split())
a=[]
for i in range(m):
  a.append(int(input()))
b=[0 for x in range(n+1)]
b[0]=1
for i in range(1,n+1):
  if i in a:
    continue
  x=b[i-1]
  if i>1:x+=b[i-2]
  b[i]=x
print(b[n]%(10**9+7))