n, m = map(int, input().split())
A = [int(input()) for i in range(m)]
dp = [0] * (n + 1)
dp[0] = 1
if 1 in A:
  dp[1] = 0
else:
  dp[1] = 1

for i in range(2, n+1):
  if i in A:
    dp[i] = 0
  else:
    dp[i] = (dp[i-1] + dp[i-2]) % (10**9 + 7)
print(dp[n])