n, m = map(int, input().split())

broken = []
for _ in range(m):
  broken.append(int(input()))
  
dp = [0] * (n + 1)

dp[0] = 1
if 1 not in broken:
  dp[1] = 1

for i in range(2, n + 1):
  if i - 1 not in broken:
    dp[i] += dp[i - 1]
  if i - 2 not in broken:
    dp[i] += dp[i - 2]
  dp[i] %= 1000000007
 
print(dp.pop())