n, m = map(int, input().split())
dp = [0] * (n + 1)
a = []
for i in range(m):
    aa = int(input())
    dp[aa] = -1
    a.append(aa)
for i in range(m - 1):
    if a[i] + 1 == a[i + 1]:
        print(0)
        exit()
mod = 10 ** 9 + 7

dp[0] = 1
if 1 in a:
    dp[1] = 0
else:
    dp[0] = 1
for i in range(1, n):
    if dp[i + 1] == -1:
        dp[i + 1] = 0
    else:
        dp[i + 1] = (dp[i] + dp[i - 1]) % mod
print(dp[n] % mod)