n, m  = map(int, input().split())
alist = [int(input()) for i in range(m)]
div_num = 1000000007

f = [1, 1]
for i in range(n-1)[::-1]:
  flag1 = True if i+1 not in alist else False
  flag2 = True if i+2 not in alist else False
  if flag1 is False and flag2 is False:
    print(0)
    exit()
  elif falg1 is False and flag2 is True:
    f = [f[1]] + [f[0]]
  elif flag1 is True and flag2 is False:
    f = [f[0]] + [f[0]]
  else:
    f = [f[0]+f[1]] + [f[0]]
     
print(int(f[0]%div_num))