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 Python (3.4.3) (judge verdict: Runtime Error)

#include <bits/stdc++.h>
using namespace std;


int main() {
	int N;
	cin>>N;
	string A,B;
	int count=0;
	ostringstream oss1,oss2;
	string As,Bs;
	for(int i=1;i<N;i++){
		for(int j=1;j<N;j++){
		oss1<<i;
		oss2<<j;
		As=oss1.str();
		Bs=oss2.str();
		if(As.at(0)==Bs.at(0)){
			count++;
			
		}
		}
	}
	cout<<count<<endl;
	return 0;
}