Kyselyt

import java.util.Scanner;

public class kyselyt {
	public static void main(String[] args) {
		Scanner in = new Scanner(System.in);
		int amountOfCases = Integer.parseInt(in.nextLine());
		for (long i = 0; i < amountOfCases; i++) {
			System.out.println(performFunction(Long.parseLong(in.nextLine())));
		}
		in.close();
	}

	public static long performFunction (long length) {
		long position = length;
		for (length = 0; (9 * (length + 2) * Math.pow(10, length + 1) - Math.pow(10, length + 2) + 1) / 9 < position; length++);
		position -= (long) (9 * (length + 1) * Math.pow(10, length) - Math.pow(10, ++length) + 1) / 9;
		long number = (long) Math.pow(10, length - 1) + (position - 1) / length;
		return ((long) ((position % length == 0) ? number % 10 : (number / (Math.pow(10, length - position % length))) % 10));

	}

}

Test 1

Group: 1

Verdict: ACCEPTED

Test 2

Group: 2

Verdict: ACCEPTED

Test 3

Group: 3

Verdict: WRONG ANSWER