Codeforces Round #462 (Div. 2) B. A Prosperous Lot

本文介绍了一个寻找特定数量环形数字的问题,需要找到一个不超过10^18的正整数n,使得其十进制表示中恰好包含k个环形部分。环形部分是指阿拉伯数字书写形式中封闭的平面区域。

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B. A Prosperous Lot
time limit per test
1 second
memory limit per test
256 megabytes
input
standard input
output
standard output

Apart from Nian, there is a daemon named Sui, which terrifies children and causes them to become sick. Parents give their children money wrapped in red packets and put them under the pillow, so that when Sui tries to approach them, it will be driven away by the fairies inside.

Big Banban is hesitating over the amount of money to give out. He considers loops to be lucky since it symbolizes unity and harmony.

He would like to find a positive integer n not greater than 1018, such that there are exactly k loops in the decimal representation of n, or determine that such n does not exist.

loop is a planar area enclosed by lines in the digits' decimal representation written in Arabic numerals. For example, there is one loop in digit 4, two loops in 8 and no loops in 5. Refer to the figure below for all exact forms.

Input

The first and only line contains an integer k (1 ≤ k ≤ 106) — the desired number of loops.

Output

Output an integer — if no such n exists, output -1; otherwise output any such n. In the latter case, your output should be a positive decimal integer not exceeding 1018.

Examples
input
Copy
2
output
462
input
Copy
6
output
8080

CF真的越来越有趣了,题目半天都没有理解大哭大哭

贼简单,不写题解了

def jisuan(s,n):
    for i in range(n/2):
        s+='8'
    return s

n=input()
if n>36:
    print -1
else:
    s=''
    s=jisuan(s,n)
    if n%2==1:
        s+='6'
    print s




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