N, M = map(int, input().split())
a = [ int(input()) for _ in range(N)]

ans = 0

step = [0 for _ in range(N + 2)]
step[1] = 1

for _ in range(M):
  i = int(input()) + 1
  step[i] = -1

for i in range(2, N + 2):
  if step[i] == -1:
    step[i] = 0
  else:
    step[i] = (step[i - 2] + step[i - 1]) % N

print (step[N] % 1000000007)
