n,m=map(int,input().split())

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

fib=[0 for i in range(n+2)]
fib[1]=1
for i in range(2,n+2):
  fib[i] = (fib[i-1]+fib[i-2]) % 1000000007

com=1
anow=-1
for i in range(m):
  a=int(input())
  if a-anow==1:
    print(0)
    exit()
  com = (com * fib[a-anow-1]) % 1000000007
  anow=a

com = (com * fib[n-anow]) % 1000000007
print(com)