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: Accepted)

import java.io.OutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.util.StringTokenizer;
import java.io.IOException;
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.InputStream;

/**
 * Built using CHelper plug-in
 * Actual solution is at the top
 *
 * @author Jaynil
 */
public class Main {
    public static void main(String[] args) {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        InputReader in = new InputReader(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        DHandstand2 solver = new DHandstand2();
        solver.solve(1, in, out);
        out.close();
    }

    static class DHandstand2 {
        public void solve(int testNumber, InputReader in, PrintWriter out) {
            int n = in.nextInt();
            int h[] = new int[100];
            long ans = 0;
            for (int i = 1; i <= n; i++) {
//            out.println((Integer.toString(i).charAt(0)-'0') * 10 + i%10);
                h[(Integer.toString(i).charAt(0) - '0') * 10 + i % 10]++;
                if ((((i % 10) * 10) + Integer.toString(i).charAt(0) - '0') % 10 != (((i % 10) * 10) + Integer.toString(i).charAt(0) - '0') / 10) {
                    ans += 2 * h[((i % 10) * 10) + Integer.toString(i).charAt(0) - '0'];
//                out.println(i + " " + 2 *h[((i % 10) * 10) + Integer.toString(i).charAt(0) - '0']);
                } else {
                    ans += 2 * (h[((i % 10) * 10) + Integer.toString(i).charAt(0) - '0'] - 1) + 1;
//                out.println(i + " " + h[((i%10)*10) + Integer.toString(i).charAt(0)-'0']);
                }
//            out.println(i + " " + h[((i%10)*10) + Integer.toString(i).charAt(0)-'0']);
            }
            out.println(ans);
        }

    }

    static class InputReader {
        public BufferedReader reader;
        public StringTokenizer tokenizer;

        public InputReader(InputStream stream) {
            reader = new BufferedReader(new InputStreamReader(stream), 32768);
            tokenizer = null;
        }

        public String next() {
            while (tokenizer == null || !tokenizer.hasMoreTokens()) {
                try {
                    tokenizer = new StringTokenizer(reader.readLine());
                } catch (IOException e) {
                    throw new RuntimeException(e);
                }
            }
            return tokenizer.nextToken();
        }

        public int nextInt() {
            return Integer.parseInt(next());
        }

    }
}