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 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)