// Nested if statement to ensure day value is compatible with month value
        if (month == 2) {
            if (day > 28) { // February has 28 days
                System.out.println("Invalid date, please enter a valid date.");
            } else {
                valid = true;
            }
        } else if (month == 4 || month == 6 || month == 9 || month == 11) {
            if (day > 30) { // April, May, September and November have 30 days
                System.out.println("Invalid date, please enter a valid date.");
            } else {
                valid = true;
            }
        } else {
            valid = true;
        }