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: Wrong Answer)

import java.util.Scanner;

class Main{
  public static void main(String[] arg){
    Scanner scan=new Scanner(System.in);
    int num=scan.nextInt();
    if(num<10){
      System.out.println(num);
    }else if(num<100){
      System.out.println(9);
    }else if(num<1000){
      System.out.println(9+(num%100)+1);
    }else if(num<10000){
      System.out.println(109);
    }else if(num<100000){
      System.out.println(109+(num%10000));
    }else if(num<1000000){
      System.out.println(90909);
    }else{
      System.out.println(90910);
    }
  }
}