import sys

n,m=map(int,input().split())
broken=set(map(int,sys.stdin))

if n==1:
  print (1)
  sys.exit()
if n==2:
  if 1 not in broken and 2 not in broken:
    print (2)
  elif 2 in broken:
    print(0)
  elif 1 in broken and 2 not in broken:
    print(1)

way = [0]*n
if 1 not in broken:
  way[0]=1
if 1 not in broken and 2 not in broken:
  way[1]=2
elif 1 in broken and 2 not in broken:
  way[1]=1
for i in range(2,n):
  if i+1 in broken:
    way[i]=0
    continue
  way[i]=(way[i-1]+way[i-2])%1000000007
print(way[n-1])
  