n,m = map(int,input().split())
li = [int(input()) for i in range(m)]
p = 1000000007
ans = 0

steps = [0]*(n+1)
steps[1] = 1
steps[2] = 2
for i in range(3,n+1):
  steps[i] = (steps[i-1] + steps[i-2])%p
if m == 0:
  print(steps[n])
else:
  if li[0] == 1:
    ans += 1
  else:
    ans += steps[li[0]-1]%p

  for i in range(m-1):
    if li[i+1] == li[i]:
      continue
    elif li[i+1] - li[i] == 1:
      ans = 0
    elif li[i+1] - li[i] == 2:
      continue
    else:
      ans *= steps[li[i+1]-li[i]-2]
      ans %= p

  if li[m-1] == n-1: 
    print(ans)
  else:
    print((ans*steps[n-li[m-1]-1])%p)