mod = 10**9 + 7

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

dp = {}
for i in range(n + 1):
    dp[i] = 1
dp[1] = 0 if 1 in a else 1
for i in range(2, n + 1):
    if i in a:
        dp[i] = 0
    else:
        dp[i] = dp[i - 1] % mod + dp[i - 2] % mod
        dp[i] %= mod

print(dp[n] % mod)
