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: Runtime Error)

import java.util.*;

public class Main {
	public static void main(String[] args) throws Exception {
		Scanner scan = new Scanner(System.in);
		String a = scan.next();
      	int b = Integer.parseInt(a);
		int count = 9;
		if (a.length() < 3) {
			System.out.println(a.charAt(1));
		} else {
			for (int i = 3; i < a.length() + 1; i++) {
				if (i % 2 == 0) {
					continue;
				}
				if (i != a.length()) {
						count +=Math.pow(10, i) - Math.pow(10, i - 1.0) - 1.0;
				}
				if (i == a.length()) {
					count += b - Math.pow(10, i -1) ;
				}
			}
				System.out.println(count);
			}
		}

	}