Problem:
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

Solution in Java8 (OpenJDK 1.8.0) (judge verdict: Wrong Answer)



import java.util.*;

class Main {
    public static void main(String args[]){

        Scanner s=new Scanner(System.in);
        Integer n= s.nextInt();
        int count=0;
        for (int i = 1; i <=n ; i++) {
            //さいしょのもじ
            int ns=String.valueOf(i).charAt(0)-'0';
            int nf=i%10;
            for (int j = 0; j <n ; j++) {
                int js=String.valueOf(j).charAt(0)-'0';
                int jf=j%10;
                if(ns==jf&&nf==js){
                    count++;
                }
            }
        }
        System.out.println(count);
    }

}