MOD = 10 ** 9 + 7

N, M = map(int, input().split())

broken = [False for _ in range(N+1)]
for _ in range(M):
	broken[int(input())] = True

dp = [0 for _ in range(N + 1)]
dp[0] = 1
dp[1] = 1

for i in range(2, N+1):
	if broken[i]:
		continue
	else:
		dp[i] = dp[i-1] + dp[i-2]
		dp[i] %= MOD
print(dp[N])
