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) {
		/*整数Nが与えられます。N 以下の正の整数のうち、(先頭に0をつけずに十進法で表記したときの) 桁数が奇数であるようなものの個数を求めてください。*/
		
		Scanner sc = new Scanner(System.in);
		
		Integer N = sc.nextInt();
		sc.close();
		
		int result = 0;
		
		for (int i = 1; i <= N;i++) {
			String test  = Integer.toString(i);
		
			if (test.length()%2 != 0) result++;
		
		}
		
		System.out.println(result);

	}

}