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