validate Month input 01 and 1?

I need an int value for both inputs. Either the user write 1 or 01 for january. So it does work for 1 - 12 but if I write 01 it does give me my own error Text. For me its importend that it is a int Value, I know that String is perfectly work.

private static BufferedReader input= new BufferedReader(new InputStreamReader(System.in));
private Output output = new Output();


public static String inputText() throws Exception {
    return input.readLine();
}

public int monatInput(String text){
    String monthNumber= "";
    boolean again = true;
    while (again) {
        System.out.print(text);
        again = false;
        try {
            monthNumber = inputText();
            int number= Integer.parseInt(monatZahl);
            int monthLength = String.valueOf(monatZahl).length();


            if (number<=1 || number>=12) {
                again = true;
                throw new Exception();
            } else if (monthLength> 3) {
                again = true;
                throw new Exception();
            }
        } catch (Exception e) {
            this.output.monatWrongInput;
        }
    }
    int converter = Integer.parseInt(monatZahl);
    return converter;

}

I hope you guys can help me to validate this problem. I seen many post about a for-loop to generate 01 digit but thats a bit different then validate as user input. Sorry for my bad english. Best regard MonsterHunter.Dev