You are given n segments on the coordinate axis Ox and the number k. The point is satisfied if it belongs to at least k segments. Find the smallest (by the number of segments) set of segments on the coordinate axis Ox which contains all satisfied points and no others.

Input

The first line contains two integers n and k (1 ≤ k ≤ n ≤ 106) — the number of segments and the value of k.

The next n lines contain two integers li, ri ( - 109 ≤ li ≤ ri ≤ 109) each — the endpoints of the i-th segment. The segments can degenerate and intersect each other. The segments are given in arbitrary order.

Output

First line contains integer m — the smallest number of segments.

Next m lines contain two integers aj, bj (aj ≤ bj) — the ends of j-th segment in the answer. The segments should be listed in the order from left to right.

Examples

Input

3 2
0 5
-3 2
3 8


Output

2
0 2
3 5


Input

3 2
0 5
-3 3
3 8


Output

1
0 5
import java.io.OutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.util.Arrays;
import java.io.IOException;
import java.util.Random;
import java.io.InputStreamReader;
import java.util.ArrayList;
import java.util.List;
import java.util.StringTokenizer;
import java.io.BufferedReader;
import java.io.InputStream;

/**
 * Built using CHelper plug-in
 * Actual solution is at the top
 *
 * @author AnandOza
 */
public class Main {
    public static void main(String[] args) {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        InputReader in = new InputReader(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        DTheUnionOfKSegments solver = new DTheUnionOfKSegments();
        solver.solve(1, in, out);
        out.close();
    }

    static class DTheUnionOfKSegments {
        public void solve(int testNumber, InputReader in, PrintWriter out) {
            int n = in.nextInt(), k = in.nextInt();

            int[] start = new int[n];
            int[] end = new int[n];
            for (int i = 0; i < n; i++) {
                start[i] = in.nextInt();
                end[i] = in.nextInt();
            }
            Util.safeSort(start);
            Util.safeSort(end);

            List<String> answer = new ArrayList<>();
            int count = 0;
            int last = Integer.MAX_VALUE;

            for (int i = 0, j = 0; i < n || j < n; ) {
                boolean incI = i != n && start[i] <= end[j];

                if (incI) {
                    count++;
                    if (count == k)
                        last = start[i];
                    i++;
                } else {
                    count--;
                    if (count == k - 1)
                        answer.add(Util.join(last, end[j]));
                    j++;
                }
            }

            out.println(answer.size());
            for (String s : answer) {
                out.println(s);
            }

        }

    }

    static class InputReader {
        public BufferedReader reader;
        public StringTokenizer tokenizer;

        public InputReader(InputStream stream) {
            reader = new BufferedReader(new InputStreamReader(stream), 32768);
            tokenizer = null;
        }

        public String next() {
            while (tokenizer == null || !tokenizer.hasMoreTokens()) {
                try {
                    tokenizer = new StringTokenizer(reader.readLine());
                } catch (IOException e) {
                    throw new RuntimeException(e);
                }
            }
            return tokenizer.nextToken();
        }

        public int nextInt() {
            return Integer.parseInt(next());
        }

    }

    static class Util {
        public static String join(int... i) {
            StringBuilder sb = new StringBuilder();
            for (int o : i) {
                sb.append(o);
                sb.append(" ");
            }
            if (sb.length() > 0) {
                sb.deleteCharAt(sb.length() - 1);
            }
            return sb.toString();
        }

        public static void safeSort(int[] x) {
            shuffle(x);
            Arrays.sort(x);
        }

        public static void shuffle(int[] x) {
            Random r = new Random();

            for (int i = 0; i <= x.length - 2; i++) {
                int j = i + r.nextInt(x.length - i);
                swap(x, i, j);
            }
        }

        public static void swap(int[] x, int i, int j) {
            int t = x[i];
            x[i] = x[j];
            x[j] = t;
        }

    }
}

