16a. Numbers 0..100 to Text

/**
 * Project: Simple_Conditions - created by borkins on 2017-03-25.
 */

import java.util.Scanner;

public class _16a_Numbers_0_100_toText
{
    public static void main(String[] args)
    {
        Scanner scan = new Scanner(System.in);

        int number = Integer.parseInt(scan.nextLine());

        int units = number % 10;
        int tenths = number / 10;

        String unitsEng = "";
        String tenthsEng = "";

        if (units == 0) {
            unitsEng = "zero";
        }
        else if (units == 1) {
            unitsEng = "one";
        }
        else if (units == 2) {
            unitsEng = "two";
        }
        else if (units == 3) {
            unitsEng = "three";
        }
        else if (units == 4) {
            unitsEng = "four";
        }
        else if (units == 5) {
            unitsEng = "five";
        }
        else if (units == 6) {
            unitsEng = "six";
        }
        else if (units == 7) {
            unitsEng = "seven";
        }
        else if (units == 8) {
            unitsEng = "eight";
        }
        else if (units == 9) {
            unitsEng = "nine";
        }

        if (tenths == 1)
        {
            if (units == 0) {
                tenthsEng = "ten";
            }
            else if (units == 1) {
                tenthsEng = "eleven";
            }
            else if (units == 2) {
                tenthsEng = "twelve";
            }
            else if (units == 3) {
                tenthsEng = "thirteen";
            }
            else if (units == 4) {
                tenthsEng = "fourteen";
            }
            else if (units == 5) {
                tenthsEng = "fifteen";
            }
            else if (units == 6) {
                tenthsEng = "sixteen";
            }
            else if (units == 7) {
                tenthsEng = "seventeen";
            }
            else if (units == 8) {
                tenthsEng = "eighteen";
            }
            else if (units == 9) {
                tenthsEng = "nineteen";
            }
        }
        else if (tenths == 2) {
            tenthsEng = "twenty";
        }
        else if (tenths == 3) {
            tenthsEng = "thirty";
        }
        else if (tenths == 4) {
            tenthsEng = "forty";
        }
        else if (tenths == 5) {
            tenthsEng = "fifty";
        }
        else if (tenths == 6) {
            tenthsEng = "sixty";
        }
        else if (tenths == 7) {
            tenthsEng = "seventy";
        }
        else if (tenths == 8) {
            tenthsEng = "eighty";
        }
        else if (tenths == 9) {
            tenthsEng = "ninety";
        }

        // If either conditions is true, print "invalid number".
        if (number < 0 || number > 100) {
            System.out.println("invalid number");
        }
        // In that point we are sure that the number is in the range 0..100.
        // If true, number is between 0 and 9, then print numbers: 'zero', 'one', 'two'...'nine'.
        else if (number < 10) {
            System.out.println(unitsEng);
        }
        // If number is between 10 and 19, print numbers: 'ten', 'eleven', 'twelve'...'nineteen'.
        // OR if number is between 20..99 AND the digit in the units is 0,
        // print numbers: 'twenty', 'thirty', 'forty'...'ninety'.
        else if (number < 20 || (number < 100 && units == 0)) {
            System.out.println(tenthsEng);
        }
        // If number is between 20 and 99, print the numbers with two words.
        else if (number < 100) {
            System.out.println(tenthsEng + " " + unitsEng);
        }
        // The number is 100, print 'one hundred'.
        else {
            System.out.println("one hundred");
        }
    }
}