n, m = map(int, input().split())
am = [int(input()) for _ in range(m)]
mod = 10**9+7
dp = [0]*(n+1)
dp[0] = 1
dp[1] = 1
for i in range(2, n+1):
    if i-1 not in am:
        dp[i] += dp[i-1]
    if i-2 not in am:
        dp[i] += dp[i-2]
    dp[i] %= mod
print(dp[n])
