public class Main {
	public static void main(String[] args) {
		Income[] incomes = new Income[] { new Income(3000), new SalaryIncome(7500), new RoyaltyIncome(12000)};
		double total = 0;
		for (Income income : incomes) {
			total += income.getTax();
		}
		System.out.println(total);
	}
	
	public class Income {

		protected double income;

		public Income(double income) {
			this.income = income;
		}

		public double getTax() {
			return income * 0.1; // 税率10%
		}

	}

	public class SalaryIncome extends Income {

		public SalaryIncome(double income) {
			super(income);
		}

		@Override
		public double getTax() {
			if (income <= 5000) {
				return 0;
			}
			return (income - 5000) * 0.2;
		}
	}

	public class RoyaltyIncome extends Income{
		public RoyaltyIncome(double income) {
			super(income);
		}
		@Override
		public double getTax() {
			return this.income * 0.2; 
		}
	}

}