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 javax.swing.text.Segment;
import java.io.*;
import java.util.*;
import java.math.*;

public class Main implements Runnable {
    public InputReader in;
    public PrintWriter out;

    public void solve() throws Exception {
        // solution goes here
        int N = in.nextInt();
        int K = in.nextInt();

        LevelChange[] levelChanges = new LevelChange[N << 1];
        for (int i = 0; i < N; i++) {
            int start = in.nextInt();
            int end = in.nextInt();
            levelChanges[i << 1] = new LevelChange(start, true);
            levelChanges[(i << 1) + 1] = new LevelChange(end, false);
        }
        Arrays.sort(levelChanges);

        int currentLevel = 0;
        ArrayList<Integer> starts = new ArrayList<>();
        ArrayList<Integer> ends = new ArrayList<>();

        for (LevelChange levelChange : levelChanges) {
            if (levelChange.increase) {
                currentLevel++;
            } else {
                currentLevel--;
            }

            if (currentLevel >= K && starts.size() == ends.size())
                starts.add(levelChange.x);
            else if (currentLevel < K && starts.size() > ends.size())
                ends.add(levelChange.x);
        }

        int segments = starts.size();
        out.println(segments);
        for (int i = 0; i < segments; i++) {
            out.print(starts.get(i));
            out.write(' ');
            out.print(ends.get(i));
            out.write('\n');
        }
    }

    static class LevelChange implements Comparable<LevelChange> {
        int x;
        boolean increase;

        public LevelChange (int x, boolean increase) {
            this.x = x;
            this.increase = increase;
        }

        @Override
        public int compareTo(LevelChange o) {
            return Integer.compare(x, o.x) == 0 ? Boolean.compare(o.increase, increase) : Integer.compare(x, o.x);
        }
    }

    public void run() {
        try {
            in = new InputReader(System.in);
            out = new PrintWriter(new BufferedWriter(new OutputStreamWriter(System.out)));
            Locale.setDefault(Locale.US);
            solve();
            out.close();
        } catch (Throwable e) {
            e.printStackTrace();
            System.exit(7);
        }
    }

    static int abs(int x) {
        return x < 0 ? -x : x;
    }

    static int max(int a, int b) {
        return a > b ? a : b;
    }

    static int min(int a, int b) {
        return a < b ? a : b;
    }

    public static void main(String args[]) {
        new Thread(null, new Main(), "Main", 1 << 28).start();
    }

    static boolean OJ = System.getProperty("ONLINE_JUDGE") != null;

    public void console(Object... objects) {
        if (!OJ) {
            out.println(Arrays.deepToString(objects));
            out.flush();
        }
    }

    @SuppressWarnings({"Duplicates", "unused"})
    static class InputReader {

        private InputStream stream;
        private byte[] buf = new byte[2048];
        private int curChar;
        private int numChars;
        private SpaceCharFilter filter;

        public InputReader() {
            this.stream = System.in;
        }

        public InputReader(InputStream stream) {
            this.stream = stream;
        }

        public InputReader(SpaceCharFilter filter) {
            this.stream = System.in;
            this.filter = filter;
        }

        public InputReader(InputStream stream, SpaceCharFilter filter) {
            this.stream = stream;
            this.filter = filter;
        }

        public int read() {
            if (curChar >= numChars) {
                curChar = 0;
                try {
                    numChars = stream.read(buf);
                } catch (IOException e) {
                    throw new InputMismatchException();
                }
                if (numChars <= 0)
                    return -1;
            }
            return buf[curChar++];
        }

        public char nextChar() {
            int c = read();
            while (isSpaceChar(c))
                c = read();
            return (char) c;
        }

        public int nextDigit() {
            int c = read();
            while (isSpaceChar(c))
                c = read();
            return c - '0';
        }

        public int nextInt() {
            int c = read();
            while (isSpaceChar(c))
                c = read();
            boolean negative = false;
            if (c == '-') {
                negative = true;
                c = read();
            }
            int res = 0;
            do {
                if (c < '0' || c > '9')
                    throw new InputMismatchException();
                res *= 10;
                res += c - '0';
                c = read();
            } while (!isSpaceChar(c));
            return negative ? -res : res;
        }

        public int[] nextInts(int N) {
            int[] nums = new int[N];
            for (int i = 0; i < N; i++)
                nums[i] = nextInt();
            return nums;
        }

        public long[] nextLongs(int N) {
            long[] nums = new long[N];
            for (int i = 0; i < N; i++)
                nums[i] = nextLong();
            return nums;
        }

        public int nextUnsignedInt() {
            int c = read();
            while (isSpaceChar(c))
                c = read();
            int res = 0;
            do {
                res *= 10;
                res += c - '0';
                c = read();
            } while (!isSpaceChar(c));
            return res;
        }

        public final long nextLong() {
            int c = read();
            while (isSpaceChar(c)) {
                c = read();
            }
            boolean negative = false;
            if (c == '-') {
                negative = true;
                c = read();
            }
            long res = 0;
            do {
                res *= 10;
                res += c - '0';
                c = read();
            } while (!isSpaceChar(c));
            return negative ? -res : res;
        }

        public final long nextUnsignedLong() {
            int c = read();
            while (isSpaceChar(c)) {
                c = read();
            }
            long res = 0;
            do {
                res *= 10;
                res += c - '0';
                c = read();
            } while (!isSpaceChar(c));
            return res;
        }

        public double nextDouble() {
            int c = read();
            while (isSpaceChar(c))
                c = read();
            long sgn = 1;
            if (c == '-') {
                sgn = -1;
                c = read();
            }
            long res = 0;
            do {
                if (c < '0' || c > '9')
                    throw new InputMismatchException();
                res *= 10;
                res += c - '0';
                c = read();
            } while (!(c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1 || c == '.'));

            if (c != '.') {
                return res * sgn;
            }
            c = read();

            long aft = 0;
            int len = 1;
            do {
                if (c < '0' || c > '9')
                    throw new InputMismatchException();
                aft *= 10;
                len *= 10;
                aft += c - '0';
                c = read();
            } while (!isSpaceChar(c));

            return res * sgn + aft / (1.0 * len);
        }

        public String nextLine() {
            int c = read();
            while (isSpaceChar(c))
                c = read();
            StringBuilder res = new StringBuilder();
            do {
                res.appendCodePoint(c);
                c = read();
            } while (!isEndChar(c));
            return res.toString();
        }

        public boolean isSpaceChar(int c) {
            if (filter != null)
                return filter.isSpaceChar(c);
            return c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1;
        }

        public boolean isEndChar(int c) {
            if (filter != null)
                return filter.isSpaceChar(c);
            return c == '\n' || c == '\r' || c == '\t' || c == -1;
        }

        public String next() {
            int c = read();
            while (isSpaceChar(c))
                c = read();
            StringBuilder res = new StringBuilder();
            do {
                res.appendCodePoint(c);
                c = read();
            } while (!isSpaceChar(c));
            return res.toString();
        }

        public char[] nextChars() {
            int c = read();
            while (isSpaceChar(c))
                c = read();
            StringBuilder res = new StringBuilder();
            do {
                res.appendCodePoint(c);
                c = read();
            } while (!isSpaceChar(c));

            char[] chars = new char[res.length()];
            res.getChars(0, chars.length, chars, 0);
            return chars;
        }

        public int[][] nextIntMatrix(int rows, int cols) {
            int[][] matrix = new int[rows][cols];
            for (int i = 0; i < rows; i++)
                for (int j = 0; j < cols; j++)
                    matrix[i][j] = nextInt();
            return matrix;
        }

        public long[][] nextLongMatrix(int rows, int cols) {
            long[][] matrix = new long[rows][cols];
            for (int i = 0; i < rows; i++)
                for (int j = 0; j < cols; j++)
                    matrix[i][j] = nextLong();
            return matrix;
        }

        public char[][] nextCharMap(int rows, int cols) {
            char[][] matrix = new char[rows][cols];
            for (int i = 0; i < rows; i++)
                for (int j = 0; j < cols; j++)
                    matrix[i][j] = nextChar();
            return matrix;
        }

        public interface SpaceCharFilter {
            public boolean isSpaceChar(int ch);
        }
    }
}