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 Ruby (2.3.3) (judge verdict: Wrong Answer)

line = gets.chomp
l=line.split("")
if l.length==1 then
  puts l[0].to_i
else
  a=l.first.to_i
  b=l.last.to_i
  ll = line.to_i
  if a>b then
    c=(ll-b)/10-1
  else
    c=(ll-a)/10
  end
  if c==1 then
    if ll>20 then
      puts 15
    else
      puts 13
    end
  else
    if a>b then
      ans=17+(c-2)*7+(c-2)*(c-3)
      ans=ans+2*b
      puts ans
    else
      ans=17+(c-2)*7+(c-2)*(c-3)
      puts ans
    end
  end  
end