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)
{
    return (int)(nu+"").charAt(0)-'0';
}



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++;
    // System.out.println("\na: "+a+"	b: "+b);
    }
    }
    }
System.out.println(count);
}
}