public class BasePremium {
    public static double getBasePremium(String vehicleType) {
        if (vehicleType.equalsIgnoreCase("2W")) {
            return 2500;
        } else if (vehicleType.equalsIgnoreCase("4W")) {
            return 4500;
        } else {
            throw new IllegalArgumentException("Invalid vehicle type.");
        }
    }
}