CSC2015.java

import java.util.*;

class Main {
    public static void main(String[] args) {

        Scanner s = new Scanner(System.in);

        String nextLine = null;
        int n = 0;
        int i = 1;
        List<Line> lines = null;
        String[] ar = null;
        Line line = null;
        while (s.hasNext()) {



            nextLine = s.next();

            if (i == 1) {
                n = Integer.parseInt(nextLine.trim());
                lines = new ArrayList<>(n);
            } else {

                if (i % 2 == 0) {
                    line = new Line();
                    line.x = Integer.parseInt(nextLine);
                } else {

                    line.y = Integer.parseInt(nextLine);
                    lines.add(line);
                    if (i == n*2 + 1) {
                        break;
                    }
                }


            }
            i++;
        }

//        System.out.println(lines);

        Collections.sort(lines, new Comparator<Line>() {
            @Override
            public int compare(Line o1, Line o2) {
               return Integer.compare(o1.y, o2.y);
            }
        });

//        System.out.println(lines);


        Set<Integer> dots = new HashSet<Integer>(n);

        for (Line l : lines) {
            int c = l.y;
            if (!l.visited) {
                dots.add(c);
                l.visited = true;
            }

            int j = lines.indexOf(l) + 1;
            while (j < lines.size()) {
                Line next = lines.get(j);
                j++;
                if (next.visited) {
                    continue;
                }

                if (next.contains(c)) {
                    next.visited = true;
                }


            }

        }

        System.out.println(dots.size());
        for (int dot : dots) {
            System.out.print(dot + " ");
        }

    }

    private static class Line {
        int x;
        int y;
        boolean visited = false;

        public boolean contains(int d ) {
            return (d >= x && d <= y);
        }

        @Override
        public String toString() {
            return "{" +
                    x +
                    ", " + y +
                    '}';
        }

        @Override
        public boolean equals(Object o) {
            if (this == o) return true;
            if (o == null || getClass() != o.getClass()) return false;

            Line line = (Line) o;

            if (x != line.x) return false;
            if (y != line.y) return false;

            return true;
        }

        @Override
        public int hashCode() {
            int result = x;
            result = 31 * result + y;
            return result;
        }
    }
}