Score : $300$ points

问题陈述

在十进制表示中，一个repunit是指所有数字均为 $1$ 的整数。按升序排列的repunit序列如下：$1, 11, 111, \ldots$。

找出第 $N$ 个恰好可以用三个repunit之和表示的最小整数。

以上为通义千问 qwen-max 翻译，仅供参考。

Problem Statement

A repunit is an integer whose digits are all $1$ in decimal representation. The repunits in ascending order are $1, 11, 111, \ldots$.

Find the $N$-th smallest integer that can be expressed as the sum of exactly three repunits.

Constraints

• $N$ is an integer between $1$ and $333$, inclusive.

Input

The input is given from Standard Input in the following format:

$N$

Output

Print the answer.

Sample Input 1

5

Sample Output 1

113

The integers that can be expressed as the sum of exactly three repunits are $3, 13, 23, 33, 113, \ldots$ in ascending order. For example, $113$ can be expressed as $113 = 1 + 1 + 111$.

Note that the three repunits do not have to be distinct.

Sample Input 2

19

Sample Output 2

2333

Sample Input 3

333

Sample Output 3

112222222233

update @ 2024/3/10 01:19:28