def fib(n):
  a, b = 0, 1
  for i in range(n):
    a, b = b, a + b
  return b

n,m=map(int,input().split())
if m==0:
  ans=fib(n)
else:
  a=[int(input()) for i in range(m)]
  ans = fib(a[0]-1)%1000000007
  for i in range(m-1):
    if a[i+1]-a[i]==1:
      ans=0
      break
    ans = ans*fib(a[i+1]-a[i]-2)%1000000007
  ans = ans*fib(n-a[m-1]-1)%1000000007
print(ans)