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.util.Arrays;
import java.util.InputMismatchException;
import java.util.ArrayList;
import java.io.OutputStreamWriter;
import java.util.NoSuchElementException;
import java.io.OutputStream;
import java.io.PrintWriter;
import java.util.Iterator;
import java.io.BufferedWriter;
import java.io.IOException;
import java.util.List;
import java.io.Writer;
import java.io.InputStream;

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

	static class TaskD {
		public void solve(int testNumber, InputReader in, OutputWriter out) {
			int n = in.readInt();
			int k = in.readInt();
			int[] l = new int[n];
			int[] r = new int[n];
			IOUtils.readIntArrays(in, l, r);
			int[] at = new int[2 * n];
			int[] delta = new int[2 * n];
			System.arraycopy(l, 0, at, 0, n);
			System.arraycopy(r, 0, at, n, n);
			Arrays.fill(delta, 0, n, 1);
			Arrays.fill(delta, n, 2 * n, -1);
			int[] order = ArrayUtils.createOrder(2 * n);
			ArrayUtils.sort(order, (a, b) -> at[a] != at[b] ? Integer.compare(at[a], at[b]) : delta[b] - delta[a]);
			int start = -1;
			List<IntIntPair> answer = new ArrayList<>();
			int current = 0;
			for (int i : order) {
				current += delta[i];
				if (current == k && delta[i] == 1) {
					start = at[i];
				} else if (current == k - 1 && delta[i] == -1) {
					answer.add(new IntIntPair(start, at[i]));
				}
			}
			out.printLine(answer.size());
			for (IntIntPair pair : answer) {
				out.printLine(pair.first, pair.second);
			}
		}

	}

	static class ArrayUtils {
		public static int[] range(int from, int to) {
			return Range.range(from, to).toArray();
		}

		public static int[] createOrder(int size) {
			return range(0, size);
		}

		public static int[] sort(int[] array, IntComparator comparator) {
			return sort(array, 0, array.length, comparator);
		}

		public static int[] sort(int[] array, int from, int to, IntComparator comparator) {
			if (from == 0 && to == array.length)
				new IntArray(array).sort(comparator);
			else
				new IntArray(array).subList(from, to).sort(comparator);
			return array;
		}

	}

	static class Sorter {
		private static final int INSERTION_THRESHOLD = 16;

		private Sorter() {
		}

		public static void sort(IntList list, IntComparator comparator) {
			quickSort(list, 0, list.size() - 1, (Integer.bitCount(Integer.highestOneBit(list.size()) - 1) * 5) >> 1, comparator);
		}

		private static void quickSort(IntList list, int from, int to, int remaining, IntComparator comparator) {
			if (to - from < INSERTION_THRESHOLD) {
				insertionSort(list, from, to, comparator);
				return;
			}
			if (remaining == 0) {
				heapSort(list, from, to, comparator);
				return;
			}
			remaining--;
			int pivotIndex = (from + to) >> 1;
			int pivot = list.get(pivotIndex);
			list.swap(pivotIndex, to);
			int storeIndex = from;
			int equalIndex = to;
			for (int i = from; i < equalIndex; i++) {
				int value = comparator.compare(list.get(i), pivot);
				if (value < 0) {
					list.swap(storeIndex++, i);
				} else if (value == 0) {
					list.swap(--equalIndex, i--);
				}
			}
			quickSort(list, from, storeIndex - 1, remaining, comparator);
			for (int i = equalIndex; i <= to; i++) {
				list.swap(storeIndex++, i);
			}
			quickSort(list, storeIndex, to, remaining, comparator);
		}

		private static void heapSort(IntList list, int from, int to, IntComparator comparator) {
			for (int i = (to + from - 1) >> 1; i >= from; i--) {
				siftDown(list, i, to, comparator, from);
			}
			for (int i = to; i > from; i--) {
				list.swap(from, i);
				siftDown(list, from, i - 1, comparator, from);
			}
		}

		private static void siftDown(IntList list, int start, int end, IntComparator comparator, int delta) {
			int value = list.get(start);
			while (true) {
				int child = ((start - delta) << 1) + 1 + delta;
				if (child > end) {
					return;
				}
				int childValue = list.get(child);
				if (child + 1 <= end) {
					int otherValue = list.get(child + 1);
					if (comparator.compare(otherValue, childValue) > 0) {
						child++;
						childValue = otherValue;
					}
				}
				if (comparator.compare(value, childValue) >= 0) {
					return;
				}
				list.swap(start, child);
				start = child;
			}
		}

		private static void insertionSort(IntList list, int from, int to, IntComparator comparator) {
			for (int i = from + 1; i <= to; i++) {
				int value = list.get(i);
				for (int j = i - 1; j >= from; j--) {
					if (comparator.compare(list.get(j), value) <= 0) {
						break;
					}
					list.swap(j, j + 1);
				}
			}
		}

	}

	static interface IntStream extends Iterable<Integer>, Comparable<IntStream> {
		public IntIterator intIterator();

		default public Iterator<Integer> iterator() {
			return new Iterator<Integer>() {
				private IntIterator it = intIterator();

				public boolean hasNext() {
					return it.isValid();
				}

				public Integer next() {
					int result = it.value();
					it.advance();
					return result;
				}
			};
		}

		default public int compareTo(IntStream c) {
			IntIterator it = intIterator();
			IntIterator jt = c.intIterator();
			while (it.isValid() && jt.isValid()) {
				int i = it.value();
				int j = jt.value();
				if (i < j) {
					return -1;
				} else if (i > j) {
					return 1;
				}
				it.advance();
				jt.advance();
			}
			if (it.isValid()) {
				return 1;
			}
			if (jt.isValid()) {
				return -1;
			}
			return 0;
		}

	}

	static class Range {
		public static IntList range(int from, int to) {
			int[] result = new int[Math.abs(from - to)];
			int current = from;
			if (from <= to) {
				for (int i = 0; i < result.length; i++) {
					result[i] = current++;
				}
			} else {
				for (int i = 0; i < result.length; i++) {
					result[i] = current--;
				}
			}
			return new IntArray(result);
		}

	}

	static interface IntCollection extends IntStream {
		public int size();

		default public void add(int value) {
			throw new UnsupportedOperationException();
		}

		default public int[] toArray() {
			int size = size();
			int[] array = new int[size];
			int i = 0;
			for (IntIterator it = intIterator(); it.isValid(); it.advance()) {
				array[i++] = it.value();
			}
			return array;
		}

		default public IntCollection addAll(IntStream values) {
			for (IntIterator it = values.intIterator(); it.isValid(); it.advance()) {
				add(it.value());
			}
			return this;
		}

	}

	static class InputReader {
		private InputStream stream;
		private byte[] buf = new byte[1024];
		private int curChar;
		private int numChars;
		private SpaceCharFilter filter;

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

		public int read() {
			if (numChars == -1)
				throw new InputMismatchException();
			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 int readInt() {
			int c = read();
			while (isSpaceChar(c))
				c = read();
			int sgn = 1;
			if (c == '-') {
				sgn = -1;
				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 res * sgn;
		}

		public boolean isSpaceChar(int c) {
			if (filter != null)
				return filter.isSpaceChar(c);
			return isWhitespace(c);
		}

		public static boolean isWhitespace(int c) {
			return c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1;
		}

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

		}

	}

	static interface IntIterator {
		public int value() throws NoSuchElementException;

		public boolean advance();

		public boolean isValid();

	}

	static class OutputWriter {
		private final PrintWriter writer;

		public OutputWriter(OutputStream outputStream) {
			writer = new PrintWriter(new BufferedWriter(new OutputStreamWriter(outputStream)));
		}

		public OutputWriter(Writer writer) {
			this.writer = new PrintWriter(writer);
		}

		public void print(Object... objects) {
			for (int i = 0; i < objects.length; i++) {
				if (i != 0)
					writer.print(' ');
				writer.print(objects[i]);
			}
		}

		public void printLine(Object... objects) {
			print(objects);
			writer.println();
		}

		public void close() {
			writer.close();
		}

		public void printLine(int i) {
			writer.println(i);
		}

	}

	static class IOUtils {
		public static void readIntArrays(InputReader in, int[]... arrays) {
			for (int i = 0; i < arrays[0].length; i++) {
				for (int j = 0; j < arrays.length; j++)
					arrays[j][i] = in.readInt();
			}
		}

	}

	static class IntIntPair implements Comparable<IntIntPair> {
		public final int first;
		public final int second;

		public IntIntPair(int first, int second) {
			this.first = first;
			this.second = second;
		}


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

			IntIntPair pair = (IntIntPair) o;

			return first == pair.first && second == pair.second;

		}


		public int hashCode() {
			int result = Integer.hashCode(first);
			result = 31 * result + Integer.hashCode(second);
			return result;
		}


		public String toString() {
			return "(" + first + "," + second + ")";
		}

		@SuppressWarnings({"unchecked"})
		public int compareTo(IntIntPair o) {
			int value = Integer.compare(first, o.first);
			if (value != 0) {
				return value;
			}
			return Integer.compare(second, o.second);
		}

	}

	static interface IntReversableCollection extends IntCollection {
	}

	static interface IntList extends IntReversableCollection {
		public abstract int get(int index);

		public abstract void set(int index, int value);

		public abstract void addAt(int index, int value);

		public abstract void removeAt(int index);

		default public void swap(int first, int second) {
			if (first == second) {
				return;
			}
			int temp = get(first);
			set(first, get(second));
			set(second, temp);
		}

		default public IntIterator intIterator() {
			return new IntIterator() {
				private int at;
				private boolean removed;

				public int value() {
					if (removed) {
						throw new IllegalStateException();
					}
					return get(at);
				}

				public boolean advance() {
					at++;
					removed = false;
					return isValid();
				}

				public boolean isValid() {
					return !removed && at < size();
				}

				public void remove() {
					removeAt(at);
					at--;
					removed = true;
				}
			};
		}


		default public void add(int value) {
			addAt(size(), value);
		}

		default public IntList sort(IntComparator comparator) {
			Sorter.sort(this, comparator);
			return this;
		}

		default public IntList subList(final int from, final int to) {
			return new IntList() {
				private final int shift;
				private final int size;

				{
					if (from < 0 || from > to || to > IntList.this.size()) {
						throw new IndexOutOfBoundsException("from = " + from + ", to = " + to + ", size = " + size());
					}
					shift = from;
					size = to - from;
				}

				public int size() {
					return size;
				}

				public int get(int at) {
					if (at < 0 || at >= size) {
						throw new IndexOutOfBoundsException("at = " + at + ", size = " + size());
					}
					return IntList.this.get(at + shift);
				}

				public void addAt(int index, int value) {
					throw new UnsupportedOperationException();
				}

				public void removeAt(int index) {
					throw new UnsupportedOperationException();
				}

				public void set(int at, int value) {
					if (at < 0 || at >= size) {
						throw new IndexOutOfBoundsException("at = " + at + ", size = " + size());
					}
					IntList.this.set(at + shift, value);
				}

				public IntList compute() {
					return new IntArrayList(this);
				}
			};
		}

	}

	static interface IntComparator {
		public int compare(int first, int second);

	}

	static abstract class IntAbstractStream implements IntStream {

		public String toString() {
			StringBuilder builder = new StringBuilder();
			boolean first = true;
			for (IntIterator it = intIterator(); it.isValid(); it.advance()) {
				if (first) {
					first = false;
				} else {
					builder.append(' ');
				}
				builder.append(it.value());
			}
			return builder.toString();
		}


		public boolean equals(Object o) {
			if (!(o instanceof IntStream)) {
				return false;
			}
			IntStream c = (IntStream) o;
			IntIterator it = intIterator();
			IntIterator jt = c.intIterator();
			while (it.isValid() && jt.isValid()) {
				if (it.value() != jt.value()) {
					return false;
				}
				it.advance();
				jt.advance();
			}
			return !it.isValid() && !jt.isValid();
		}


		public int hashCode() {
			int result = 0;
			for (IntIterator it = intIterator(); it.isValid(); it.advance()) {
				result *= 31;
				result += it.value();
			}
			return result;
		}

	}

	static class IntArray extends IntAbstractStream implements IntList {
		private int[] data;

		public IntArray(int[] arr) {
			data = arr;
		}

		public int size() {
			return data.length;
		}

		public int get(int at) {
			return data[at];
		}

		public void addAt(int index, int value) {
			throw new UnsupportedOperationException();
		}

		public void removeAt(int index) {
			throw new UnsupportedOperationException();
		}

		public void set(int index, int value) {
			data[index] = value;
		}

	}

	static class IntArrayList extends IntAbstractStream implements IntList {
		private int size;
		private int[] data;

		public IntArrayList() {
			this(3);
		}

		public IntArrayList(int capacity) {
			data = new int[capacity];
		}

		public IntArrayList(IntCollection c) {
			this(c.size());
			addAll(c);
		}

		public IntArrayList(IntStream c) {
			this();
			if (c instanceof IntCollection) {
				ensureCapacity(((IntCollection) c).size());
			}
			addAll(c);
		}

		public IntArrayList(IntArrayList c) {
			size = c.size();
			data = c.data.clone();
		}

		public IntArrayList(int[] arr) {
			size = arr.length;
			data = arr.clone();
		}

		public int size() {
			return size;
		}

		public int get(int at) {
			if (at >= size) {
				throw new IndexOutOfBoundsException("at = " + at + ", size = " + size);
			}
			return data[at];
		}

		private void ensureCapacity(int capacity) {
			if (data.length >= capacity) {
				return;
			}
			capacity = Math.max(2 * data.length, capacity);
			data = Arrays.copyOf(data, capacity);
		}

		public void addAt(int index, int value) {
			ensureCapacity(size + 1);
			if (index > size || index < 0) {
				throw new IndexOutOfBoundsException("at = " + index + ", size = " + size);
			}
			if (index != size) {
				System.arraycopy(data, index, data, index + 1, size - index);
			}
			data[index] = value;
			size++;
		}

		public void removeAt(int index) {
			if (index >= size || index < 0) {
				throw new IndexOutOfBoundsException("at = " + index + ", size = " + size);
			}
			if (index != size - 1) {
				System.arraycopy(data, index + 1, data, index, size - index - 1);
			}
			size--;
		}

		public void set(int index, int value) {
			if (index >= size) {
				throw new IndexOutOfBoundsException("at = " + index + ", size = " + size);
			}
			data[index] = value;
		}

	}
}

