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

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])