N, M = map(int, input().split())
a = [int(input()) for _ in range(M)]
dp = [0]*(N+1)
dp[0] = 1
for i in range(1, N+1):
  if i in a:
    continue
  if i > 1:
    dp[i] = (dp[i-1] + dp[i-2]) % 1000000007
  else:
    dp[i] = dp[0] % 1000000007
print(dp[N])