Exam 24 April 2016 01. Поправка на плочки v2

import java.math.BigDecimal;
import java.text.DecimalFormat;
import java.util.Scanner;

/**
 * Created by todor on 16.02.2017 г..
 */
public class Dummy {

    public static void main(String[] args) {
        Scanner scan = new Scanner(System.in);
        int squareAreaSideSize = Integer.parseInt(scan.nextLine());
        double tileWidth = Double.parseDouble(scan.nextLine());
        double tileHeight = Double.parseDouble(scan.nextLine());
        int benchWidth = Integer.parseInt(scan.nextLine());
        int benchHeight = Integer.parseInt(scan.nextLine());
        BigDecimal tileTime = new BigDecimal("0.2");

        double benchArea  = benchWidth * benchHeight;
        BigDecimal squareAreaWithoutBench = new BigDecimal(String.valueOf(squareAreaSideSize * squareAreaSideSize - benchArea));

        BigDecimal singleTileArea = new BigDecimal(String.valueOf(tileWidth * tileHeight));

        DecimalFormat df = new DecimalFormat("#.############");

        BigDecimal talesNeeded = squareAreaWithoutBench.divide(singleTileArea, 30, BigDecimal.ROUND_HALF_UP);
        BigDecimal finishTime =  talesNeeded.multiply(tileTime);
        talesNeeded = talesNeeded.setScale(bdLength(talesNeeded, 16), BigDecimal.ROUND_HALF_UP);
        finishTime = finishTime.setScale(bdLength(finishTime, 16), BigDecimal.ROUND_HALF_UP);

        System.out.println(df.format(talesNeeded));
        System.out.println(df.format(finishTime));
    }

    private static int bdLength(BigDecimal bdNumber, int numberLength) {
        return numberLength - (bdNumber.toPlainString().indexOf('.')) - 1;
    }
}