import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.io.PrintWriter;
import java.util.Arrays;
import java.util.TreeMap;

public class Main {

	public static void main(String[] args) {
		InputStream inputStream = System.in;
		OutputStream outputStream = System.out;
		MyInput in = new MyInput(inputStream);
		PrintWriter out = new PrintWriter(outputStream);
		TaskX solver = new TaskX();
		solver.solve(1, in, out);
		out.close();
	}

	static int INF = 1 << 30;
	static long LINF = 1L << 55;
	static int MOD = 1000000007;
	static int[] mh4 = { 0, -1, 1, 0 };
	static int[] mw4 = { -1, 0, 0, 1 };
	static int[] mh8 = { -1, -1, -1, 0, 0, 1, 1, 1 };
	static int[] mw8 = { -1, 0, 1, -1, 1, -1, 0, 1 };

	static class TaskX {

		public void solve(int testNumber, MyInput in, PrintWriter out) {

			int n = in.nextInt(), k = in.nextInt();
			P[] p = new P[n], psum = new P[n];
			int[] xs = new int[n], ys = new int[n];
			for (int i = 0; i < n; i++) {
				int x = in.nextInt(), y = in.nextInt();
				p[i] = new P(x, y);
				psum[i] = new P(x, y);
				xs[i] = x;
				ys[i] = y;
			}
			Arrays.sort(xs);
			Arrays.sort(ys);

			int idx = 1;
			TreeMap<Integer, Integer> mapx = new TreeMap<>();
			for (int i = 0; i < n; i++) {
				mapx.put(xs[i], idx++);
			}

			for (int i = 0; i < n; i++) {
				psum[i].x = mapx.get(psum[i].x);
			}

			idx = 1;
			TreeMap<Integer, Integer> mapy = new TreeMap<>();
			for (int i = 0; i < n; i++) {
				mapy.put(ys[i], idx++);
			}

			for (int i = 0; i < n; i++) {
				psum[i].y = mapy.get(psum[i].y);
			}


			int[][] sum = new int[100][100];
			for (P pp : psum) {
				sum[pp.x][pp.y]++;
			}

			for (int i = 1; i < 100; i++) {
				for (int j = 1; j < 100; j++) {
					sum[i][j] += sum[i-1][j];
					sum[i][j] += sum[i][j-1];
					sum[i][j] -= sum[i-1][j-1];
				}
			}

			long ans = Long.MAX_VALUE;
			for (int i = 0; i < n; i++) {
				for (int j = i+1; j < n; j++) {
					for (int l = 0; l < n; l++) {
						for (int m = l+1; m < n; m++) {
							int x1 = mapx.get(xs[i]), x2 = mapx.get(xs[j]);
							int y1 = mapy.get(ys[l]), y2 = mapy.get(ys[m]);
							int cnt = get(x1, y1, x2, y2, sum);
							if (cnt >= k) {
								ans = Math.min(ans, (long)(xs[j] - xs[i]) * (long)(ys[m] - ys[l]));
							}
						}
					}
				}
			}

			out.println(ans);
		}

		int get(int x1, int y1, int x2, int y2, int[][] sum) {

			int res = sum[x2][y2];
			res -= sum[x1-1][y2];
			res -= sum[x2][y1-1];
			res += sum[x1-1][y1-1];

			return res;
		}

		class P {
			int x, y;

			public P(int x, int y) {
				super();
				this.x = x;
				this.y = y;
			}

			@Override
			public String toString() {
				return "P [x=" + x + ", y=" + y + "]";
			}

		}
	}

	static class MyInput {
		private final BufferedReader in;
		private static int pos;
		private static int readLen;
		private static final char[] buffer = new char[1024 * 8];
		private static char[] str = new char[500 * 8 * 2];
		private static boolean[] isDigit = new boolean[256];
		private static boolean[] isSpace = new boolean[256];
		private static boolean[] isLineSep = new boolean[256];

		static {
			for (int i = 0; i < 10; i++) {
				isDigit['0' + i] = true;
			}
			isDigit['-'] = true;
			isSpace[' '] = isSpace['\r'] = isSpace['\n'] = isSpace['\t'] = true;
			isLineSep['\r'] = isLineSep['\n'] = true;
		}

		public MyInput(InputStream is) {
			in = new BufferedReader(new InputStreamReader(is));
		}

		public int read() {
			if (pos >= readLen) {
				pos = 0;
				try {
					readLen = in.read(buffer);
				} catch (IOException e) {
					throw new RuntimeException();
				}
				if (readLen <= 0) {
					throw new MyInput.EndOfFileRuntimeException();
				}
			}
			return buffer[pos++];
		}

		public int nextInt() {
			int len = 0;
			str[len++] = nextChar();
			len = reads(len, isSpace);
			int i = 0;
			int ret = 0;
			if (str[0] == '-') {
				i = 1;
			}
			for (; i < len; i++)
				ret = ret * 10 + str[i] - '0';
			if (str[0] == '-') {
				ret = -ret;
			}
			return ret;
		}

		public long nextLong() {
			int len = 0;
			str[len++] = nextChar();
			len = reads(len, isSpace);
			int i = 0;
			long ret = 0;
			if (str[0] == '-') {
				i = 1;
			}
			for (; i < len; i++)
				ret = ret * 10 + str[i] - '0';
			if (str[0] == '-') {
				ret = -ret;
			}
			return ret;
		}

		public char nextChar() {
			while (true) {
				final int c = read();
				if (!isSpace[c]) {
					return (char) c;
				}
			}
		}

		public String nextString() {
			return new String(nextChars());
		}

		public char[] nextChars() {
			int len = 0;
			str[len++] = nextChar();
			len = reads(len, isSpace);
			return Arrays.copyOf(str, len);
		}

		public char[][] next2DChars(int h, int w) {
			char[][] s = new char[h][w];
			for (int i = 0; i < h; i++) {
				s[i] = nextChars();
			}
			return s;
		}

		int reads(int len, boolean[] accept) {
			try {
				while (true) {
					final int c = read();
					if (accept[c]) {
						break;
					}
					if (str.length == len) {
						char[] rep = new char[str.length * 3 / 2];
						System.arraycopy(str, 0, rep, 0, str.length);
						str = rep;
					}
					str[len++] = (char) c;
				}
			} catch (MyInput.EndOfFileRuntimeException e) {
			}
			return len;
		}

		public int[] nextIntArray(final int n) {
			final int[] res = new int[n];
			for (int i = 0; i < n; i++) {
				res[i] = nextInt();
			}
			return res;
		}

		public int[] nextIntArray1Index(final int n) {
			final int[] res = new int[n + 1];
			for (int i = 1; i < n + 1; i++) {
				res[i] = nextInt();
			}
			return res;
		}

		public int[] nextIntArrayDec(final int n) {
			final int[] res = new int[n];
			for (int i = 0; i < n; i++) {
				res[i] = nextInt() - 1;
			}
			return res;
		}

		public long[] nextLongArray(final int n) {
			final long[] res = new long[n];
			for (int i = 0; i < n; i++) {
				res[i] = nextLong();
			}
			return res;
		}

		public long[] nextLongArray1Index(final int n) {
			final long[] res = new long[n + 1];
			for (int i = 1; i < n + 1; i++) {
				res[i] = nextLong();
			}
			return res;
		}

		public long[] nextLongArrayDec(final int n) {
			final long[] res = new long[n];
			for (int i = 0; i < n; i++) {
				res[i] = nextLong() - 1;
			}
			return res;
		}

		public double nextDouble() {
			return Double.parseDouble(nextString());
		}

		public double[] nextDoubleArray(int n) {
			double[] res = new double[n];
			for (int i = 0; i < n; i++) {
				res[i] = nextDouble();
			}
			return res;
		}

		static class EndOfFileRuntimeException extends RuntimeException {
		}

	}

}


Measured memory_bytes: 40240