import collections
mod = 10 ** 9 + 7
N, M = map(int, input().split())
a = collections.deque([])
for _ in range(M):
    a_m = int(input())
    if len(a) > 0 and a_m == a[-1] + 1:
        print(0)
        exit()
    a.append(a_m)

dp = [1]

if len(a) > 0 and 1 != a[0]:
    dp.append(1)
else:
    dp.append(0)
    a.popleft()

for i in range(2, N + 1):
    if len(a) > 0:
        if i != a[0]:
            tmp = dp[0] + dp[1]
        else:
            tmp = 0
            a.popleft()
    else:
        tmp = dp[0] + dp[1]
    dp[0] = dp[1]
    dp[1] = tmp

print(dp[-1] % mod)
