n, m = map(int, input().split())
l = [int(input())-1 for _ in range(m)]
res = [0, 1]
skip = 0

if m != 0:
  for i in range(n):
    if i == l[skip]:
      res[0] = res[1]
      res[1] = 0
      if skip < m-1:
        skip += 1
    else:
      tmp = res[1]
      res[1] += res[0]
      res[0] = tmp
      res[1] %= 10**9 + 7
      res[0] %= 10**9 + 7
else:
    tmp = res[1]
    res[1] += res[0]
    res[0] = tmp
    res[1] %= 10**9 + 7
    res[0] %= 10**9 + 7
      
print(res[1])