n, m  = map(int, input().split())
f = [0 for i in range(n)]
f[-2:] = [1, 1]
for i in range(m):
  f[int(input())-1] = -1

div_num = 1000000007

for i in range(n-2)[::-1]:
  if f[i] == -1:
    continue
  if f[i+1] == -1 and f[i+2] == -1:
    print(0)
    exit()
  elif f[i+1] == -1 and f[i+2] != -1:
    f[i] = f[i+2]
  elif f[i+1] != -1 and f[i+2] == -1:
    f[i] = f[i+1]
  else:
    f[i] = f[i+1]+f[i+2]

if f[0] != -1 and f[1] != -1:
  print(int((f[0]+f[1])%div_num))
elif f[0] == -1 and f[1] != -1:
  print(int(f[1]%div_num))
elif f[0] != -1 and f[1] == -1:
  print(int(f[0]%div_num))
else:
  print(0)