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: Time Limit Exceeded)

import java.util.Scanner;
public class Main {
	
	static int getfirst(int nu)
	{
		int fir=0;
		while(nu>0)
		{
			fir=nu%10;
			nu=nu/10;
		}
		return fir;
    }
	public static void main(String[] args) {
		Scanner sc=new Scanner(System.in);
		int val,count=0,a,b;
		val=sc.nextInt();
		
		
			int af,al,bf,bl;
			for(a=1;a<=val;a++)
			{
				for(b=0;b<=val;b++)
				{
					af=getfirst(a);
					al=a%10;
					bf=getfirst(b);
					bl=b%10;
					if(af==bl && al==bf)
					{
						count++;
					}
				}	
				b=0;
			}
			System.out.println(count);
		}
	}