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.*;
 
public class Main{
	public static void main(String[] args){
    	Scanner scan = new Scanner (System.in);
      	int n = scan.nextInt();	
      	int ans = 0;
      	if(n >= 10000){
        	ans += (n % 10000) + 1;
        }
      	if(n >= 100){
        	ans += (n % 100) + 1;
        }
      	if(n >= 10){
        	ans += 9;
        }
      	else {
        	ans += n + 1;
        }
      System.out.print(ans);
    }
}