DouKaku?

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.Set;
import java.util.SortedSet;
import java.util.TreeSet;

public class Sample138 {
    public static final int MAX_COUNT = 30;
    private final SortedSet<Integer> set = new TreeSet<Integer>();

    public Sample138() {
        for (int index = 1; index <= MAX_COUNT; index++) {
            set.add(index);
        }
    }
    public void delete(int number) {
        set.remove(number);
    }
    public Set<Integer> calc() {
        return set;
    }

    public static void main(String[] args) {
        BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
        try {
            Sample138 sample = new Sample138();
            for (int index = 0; index < 28; index++) {
                sample.delete(Integer.parseInt(reader.readLine()));
            }
            Set<Integer> result = sample.calc();
            for (int i: result) {
                System.out.println(i);
            }
        } catch (IOException ex) {
            ex.printStackTrace();
        }
    }
}