n,m = map(int,raw_input().split())
a = []
buf = -111
for q in range(m):
  a.append(int( raw_input() ))
  buf = a[q]
  if buf - a[q] == 1:
    print 0
    exit(0)

if n==1:
  print 1
  exit(0)
if n==2:
  if m==1:
    print 0
    exit(0)
  if m==0:
    print 2
    exit(0)

now = [-1]*100001

if m == 0:
  now[0] = 1
  now[1] = 1
  for q in range(2,n+1):
    now[q] = (now[q-1] + now[q-2]) % 1000000007
  print now[q] % 1000000007
  exit(0)
    
now[0] = 1
if a[0] == 1: now[1] = 0
else: now[1] = 1

for q in a:
  now[q] = 0

for q in range(2,n+1):
  if now[q] != -1: continue
  now[q] = (now[q-1] + now[q-2]) % 1000000007
  
print now[q] % 1000000007