Homework parsing numbers

import java.io.IOException;
import java.util.Scanner;

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

        int input = Integer.parseInt(scan.nextLine());
        System.out.println(numberParsing(input));

    }

    public static String numberParsing(int value) {
        if (value < 1 || value > 3999) {
            return "Invalid number";
        }
        StringBuilder s = new StringBuilder();
        while (value >= 1000) {
            s.append("M");
            value -= 1000;
        }
        while (value >= 900) {
            s.append("CM");
            value -= 900;
        }
        while (value >= 500) {
            s.append("D");
            value -= 500;
        }
        while (value >= 400) {
            s.append("CD");
            value -= 400;
        }
        while (value >= 100) {
            s.append("C");
            value -= 100;
        }
        while (value >= 90) {
            s.append("XC");
            value -= 90;
        }
        while (value >= 50) {
            s.append("L");
            value -= 50;
        }
        while (value >= 40) {
            s.append("XL");
            value -= 40;
        }
        while (value >= 10) {
            s.append("X");
            value -= 10;
        }
        while (value >= 9) {
            s.append("IX");
            value -= 9;
        }
        while (value >= 5) {
            s.append("V");
            value -= 5;
        }
        while (value >= 4) {
            s.append("IV");
            value -= 4;
        }
        while (value >= 1) {
            s.append("I");
            value -= 1;
        }
        return s.toString();
    }
}