#D4668. Handstand 2
Handstand 2
Handstand 2
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.
Examples
Input
25
Output
17
Input
1
Output
1
Input
100
Output
108
Input
2020
Output
40812
Input
200000
Output
400000008
inputFormat
input are integers.
Input
Input is given from Standard Input in the following format:
N
outputFormat
Output
Print the answer.
Examples
Input
25
Output
17
Input
1
Output
1
Input
100
Output
108
Input
2020
Output
40812
Input
200000
Output
400000008
样例
202040812