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 Fortran (gfortran v4.8.4) (judge verdict: Accepted)

program ABC152F
    implicit none
    integer::N
    integer::MS(9,9)=0
    integer::i,j
    integer::ANS=0
    read*,N
    do i=1,N
        if(mod(i,10)/=0)then
            MS(S(i),mod(i,10))=MS(S(i),mod(i,10))+1
        endif
    end do
    do i=1,9
        do j=1,9
            ANS=ANS+MS(i,j)*MS(j,i)
        end do
    end do
    print"(i0)",ANS
contains
function S(Num)
    integer::num
    integer::k
    integer::S
    S=10
    do k=0,6
        if(NUM/10**k/=0)then
        S=min(S,NUM/10**k)
        endif
    end do
end function
end program ABC152F