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 Go (1.6) (judge verdict: Time Limit Exceeded)

package main

import ("fmt"
     "strconv"  )
func main(){
var n int
  fmt.Scan(&n)
  c:=0
  
  s :=[]string{}
  for i:=1;i<=n;i++{
    s=append(s,strconv.Itoa(i))
  }
  //fmt.Println(s)
  for _,v1 :=range s{
    for _,v2 :=range s{
      if v1[0]==v2[len(v2)-1] && v1[len(v1)-1]==v2[0]{
      c=c+1
      }
    }
  }
  fmt.Println(c)
  

}