101523: [AtCoder]ABC152 D - Handstand 2

Memory Limit:256 MB Time Limit:2 S
Judge Style:Text Compare Creator:
Submit:0 Solved:0

Description

Score : $400$ points

Problem Statement

Given is a positive integer $N$.
Find the number of pairs $(A, B)$ of positive integers not greater than $N$ that satisfy the following condition:

  • When $A$ and $B$ are written in base ten without leading zeros, the last digit of $A$ is equal to the first digit of $B$, and the first digit of $A$ is equal to the last digit of $B$.

Constraints

  • $1 \leq N \leq 2 \times 10^5$
  • All values in input are integers.

Input

Input is given from Standard Input in the following format:

$N$

Output

Print the answer.


Sample Input 1

25

Sample Output 1

17

The following $17$ pairs satisfy the condition: $(1,1)$, $(1,11)$, $(2,2)$, $(2,22)$, $(3,3)$, $(4,4)$, $(5,5)$, $(6,6)$, $(7,7)$, $(8,8)$, $(9,9)$, $(11,1)$, $(11,11)$, $(12,21)$, $(21,12)$, $(22,2)$, and $(22,22)$.


Sample Input 2

1

Sample Output 2

1

Sample Input 3

100

Sample Output 3

108

Sample Input 4

2020

Sample Output 4

40812

Sample Input 5

200000

Sample Output 5

400000008

Input

题意翻译

## AT4828[ABC152D]翻译: ​ 给定一个数 $n$ ,考虑从 $[1,n]$ 中任意选出两个数(两数可以相等)组成有序数对 $(A,B)$ 。 ​ 求出有多少个有序数对 $(A,B)$ 满足 $A$ 的第一位数字等于 $B$ 的最后一位数字,且 $A$ 的最后一位数字等于 $B$ 的第一位数字。

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