Digits Sequence (Hard Edition)
题意翻译
## 题目描述
序列123456789101112131415161718192021222324252627282930313233343536...是无穷无尽的,现在你要输出它的第k项。
## 输入格式
一个整数k(k<=$10^{12})$。
## 输出格式
"题目描述"中的序列的第k项。
题目描述
Let's write all the positive integer numbers one after another from $ 1 $ without any delimiters (i.e. as a single string). It will be the infinite sequence starting with 123456789101112131415161718192021222324252627282930313233343536...
Your task is to print the $ k $ -th digit of this sequence.
输入输出格式
输入格式
The first and only line contains integer $ k $ ( $ 1 \le k \le 10^{12} $ ) — the position to process ( $ 1 $ -based index).
输出格式
Print the $ k $ -th digit of the resulting infinite sequence.
输入输出样例
输入样例 #1
7
输出样例 #1
7
输入样例 #2
21
输出样例 #2
5