import sys
input = sys.stdin.readline
N, M = [int(x) for x in input().strip().split()]
A = [int(input()) for _ in range(M)]
s = 1
s_ = 0
for n in range(1, N+1):
  if n in A:
    s, s_ = 0, s
    continue
  s, s_ = s + s_, s
print(s % (10 ** 9 + 7))
