N, M=map(int, input().split())
if M>0:
  a=[int(input()) for i in range(M)]

  if a[0]==1:
    way=[1, 0]
    a.remove(1)
  else:
    way=[1, 1]
else:
  way=[1, 1]
  
for i in range(2, N+1):
  if len(a)>0:
    if i==a[0]:
      a.remove(i)
      way=[way[1], 0]
    else:
      way=[way[1], sum(way)]
  else:
    way=[way[1], sum(way)]
    
print(way[1]%1000000007)