import java.util.ArrayList;
import java.util.Arrays;
import java.util.HashSet;
import java.util.List;
import java.util.Objects;
import java.util.Scanner;
import java.util.Set;

public class CoveringSegments {

    public static class Segment implements Comparable<Segment> {
        int start, end;

        Segment(int start, int end) {
            this.start = start;
            this.end = end;
        }

        public int compareTo(Segment that) {
            if (this.start > that.start)
                return 1;
            if (this.start == that.start) {
                if (this.end > that.end)
                    return 1;
                else if (this.end == that.end) {
                    return 0;
                } else
                    return -1;
            }
            return -1;
        }

        @Override
        public boolean equals(Object o) {
            if (o == this)
                return true;
            if (!(o instanceof Segment)) {
                return false;
            }
            Segment s = (Segment) o;
            return start == s.start && end == s.end;
        }

        @Override
        public int hashCode() {
            return Objects.hash(start, end);
        }

    }

    public static void main(String[] args) {
//        Scanner scanner = new Scanner(System.in);
//        int n = scanner.nextInt();
//        Set<Segment> segments = new HashSet<Segment>();
//        for (int i = 0; i < n; i++) {
//            int start, end;
//            start = scanner.nextInt();
//            end = scanner.nextInt();
//            segments.add(new Segment(start, end));
//        }
//        Segment[] s = segments.stream().toArray(Segment[]::new);
//        Arrays.sort(s);
//        int[] points = getOptimalPoints(s);
//        System.out.println(points.length);
//        for (int point : points) {
//            System.out.print(point + " ");
//        }
        Scanner scanner = new Scanner(System.in);
        int n = scanner.nextInt();
        Segment[] segments = new Segment[n];
        for (int i = 0; i < n; i++) {
            int start, end;
            start = scanner.nextInt();
            end = scanner.nextInt();
            segments[i] = new Segment(start, end);
        }
        Set<Segment> s = new HashSet<Segment>(Arrays.asList(segments));
        Segment[] newArray = s.stream().toArray(Segment[]::new);
        Arrays.sort(newArray);
        int[] points = getOptimalPoints(newArray);
        System.out.println(points.length);
        for (int point : points) {
            System.out.print(point + " ");
        }
    }

    public static int[] getOptimalPoints(Segment[] s) {
        int index = 0;
        List<Integer> points = new ArrayList<Integer>();
        while (index < s.length) {
            points.add(s[index].end);
            index = index + 1;
            while (index < s.length && s[index].start <= points.get(points.size() - 1).intValue()) {
                if (s[index].end < points.get(points.size() - 1).intValue())
                    points.set(points.size() - 1, s[index].end);
                index = index + 1;
            }
        }
        return points.stream().mapToInt(i -> i).toArray();
    }

}