import java.util.TreeMap;

public class Convertor {

    private TreeMap<Integer, String> map;

    public Convertor() {
        map = new TreeMap<>();
        map.put(1000, "M");
        map.put(900, "CM");
        map.put(500, "D");
        map.put(400, "CD");
        map.put(100, "C");
        map.put(90, "XC");
        map.put(50, "L");
        map.put(40, "XL");
        map.put(10, "X");
        map.put(9, "IX");
        map.put(5, "V");
        map.put(4, "IV");
        map.put(1, "I");
    }

    public String arabicToRomanNumber(int number) {

        if (number <= 0 || number >= 4001) {
            throw new IllegalArgumentException("Out of range!");
        }

        int transformedNumber = 0;
        StringBuilder romanNum = new StringBuilder();

        while (number != 0) {
            transformedNumber = map.floorKey(number);
            String toBeAdded = map.get(transformedNumber);
            number -= transformedNumber;
            romanNum.append(toBeAdded);
        }

        return romanNum.toString();
    }


}