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.Scanner;

public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		String str = sc.nextLine();
		int n = Integer.parseInt(str);

		//		int len = str.length();
		//		len = len / 2 + 1;
		int count = 0;

		int i = 1;
		while (i <= n) {
			if (String.valueOf(i).length() % 2 == 0) {
				i = i * 10;
				continue;
			}
			count++;
			i++;
		}

		//		for (int i = 0; i <= len; i++) {
		//			if (i % 2 != 0) {
		//				count++;
		//			}
		//			if (i >= n) {
		//				break;
		//			}
		//		}

		System.out.println(count);

		sc.close();
	}
}