mod = 10**9+7
n, m = map(int, input().split())
a = [int(input()) for _ in range(m)]
count = [0 for _ in range(n+1)]
for num in a:
  count[num] = -1
count[1] = 1
if len(count) >= 3:
  count[2] = 1
for i in range(2, n+1):
  if count[i] != -1:
    count[i] += (count[i-1] + count[i-2])%mod
  else:
    count[i] = 0

print(count[-1])