N, M  = map(int, input().split())
a  = []
for _ in range(M):
  a.append(int(input()))
sdic  = {}
nn1 = 1
nn2 = 0
for n in reversed(range(N)):
  if n in a:
    nn2 = nn1
    nn1 = 0
    continue
  t = nn1 + nn2
  if t == 0:
    print(0)
    quit()
  nn2 = nn1
  nn1 = t
  
print(nn1%1000000007)