Problem:
Score : 200 points

Problem Statement

Given is an integer N. Find the number of positive integers less than or equal to N that have an odd number of digits (in base ten without leading zeros).

Constraints

1 \leq N \leq 10^5

Input

Input is given from Standard Input in the following format:

N

Output

Print the number of positive integers less than or equal to N that have an odd number of digits.

Sample Input 1

11

Sample Output 1

9

Among the positive integers less than or equal to 11, nine integers have an odd number of digits: 1, 2, \ldots, 9.

Sample Input 2

136

Sample Output 2

46

In addition to 1, 2, \ldots, 9, another 37 integers also have an odd number of digits: 100, 101, \ldots, 136.

Sample Input 3

100000

Sample Output 3

90909

Solution in Java8 (OpenJDK 1.8.0) (judge verdict: Accepted)

import java.util.*;

public class Main {
  public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
    int number, count;
    number = Integer.parseInt(sc.next());
    if(number < 9) {
      count = number;
    } else if(number < 100) {
      count = 9;
    } else if(number < 999) {
      count = 9 + (number - 99);
    } else if(number < 10000) {
      count = 909;
    } else if(number < 99999) {
      count = 9 + 900 + (number - 9999);
    } else {
      count = 90909;
    }
    System.out.println(count);
  }
}