n, m = map(int, input().split())
p = {int(input()) for _ in range(m)}
s = 10 ** 9 + 7

dp = [0] * (n + 1)
dp[0] = 1
dp[1] = 1
if 1 in p:
    dp[1] = 0

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