import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.List;

class Application {

    static class GradeAverageCalculator {

        public double calculateAverage(List<Integer> grades) {
            if (grades == null || grades.isEmpty()) {
                return 0.0;
            }

            if (grades.size() > 2) {
                Integer min = Collections.min(grades);
                Integer max = Collections.max(grades);

                grades.remove(min);
                grades.remove(max);
            }

            return calculateAverageInternal(grades);
        }

        private double calculateAverageInternal(List<Integer> grades) {
            double sum = 0;
            for (Integer grade : grades) {
                sum += grade;
            }
            return sum / grades.size();

        }

    }

    public static void main(String[] args) throws java.lang.Exception {

        GradeAverageCalculator calculator = new GradeAverageCalculator();

        if (calculator.calculateAverage(new ArrayList<>()) == 0) {
            System.out.println("OK");
        } else {
            System.out.println("NIE OK");
        }

        if (calculator.calculateAverage(new ArrayList<>(Arrays.asList(1, 2))) == 1.5) {
            System.out.println("OK");
        } else {
            System.out.println("NIE OK");
        }

        if (calculator.calculateAverage(new ArrayList<>(Arrays.asList(1, 2, 5))) == 2) {
            System.out.println("OK");
        } else {
            System.out.println("NIE OK");
        }


    }
}