n, m = map(int, input().split())
a = [0]*m
for i in range(m):
  a[i] = int(input())

up = [0]*(m+1)
if m == 0:
  up[0] = n
else:
  up[0] = a[0]-1
  up[m] = n - a[m-1]-1
  for i in range(m-1):
    up[i+1] = a[i+1]-a[i]-2

ans = 1
if -1 in up:
  ans = 0
else:
  f = [0]*(max(up)+1)
  f[0] = 1
  f[1] = 1
  for i in range(2, max(up)+1):
    f[i] = f[i-1] + f[i-2]
  for i in range(m+1):
    ans *= f[up[i]]

print(ans % 1000000007)