n, m = map(int, input().split())
a = [0] + [int(input()) for _ in range(m)]

dp = [0] * (n + 1)
dp[0] = 1
if 1 in a:
    dp[1] = 0
else:
    dp[1] = 1
MOD = 10 ** 9 + 7

for i in range(2, n + 1):
    if i in a:
        continue
    dp[i] = dp[i - 1] + dp[i - 2]
    dp[i] %= MOD

print(dp[-1])
