import java.util.Arrays;

public class Main {

  private static void solve() {
    int n = ni();
    long k = nl();
    int[] a = na(n);
    Arrays.sort(a);


    long ok = Long.MAX_VALUE / 2;
    long ng = Long.MIN_VALUE / 2;
    while (Math.abs(ok - ng) > 1) {
      long v = (ok + ng) / 2;

      if (f(v, a) >= k) {
        ok = v;
      } else {
        ng = v;
      }
    }
    System.out.println(ok);
  }

  // x以下のペアの数
  private static long f(long x, int[] a) {
    int n = a.length;
    long ret = 0;
    for (int i = 0; i < n; i++) {

      int ng = a[i] > 0 ? n : i;
      int ok = a[i] > 0 ? i : n;
      while (Math.abs(ng - ok) > 1) {
        int k = (ng + ok) / 2;

        if ((long) a[i] * a[k] <= x) {
          ok = k;
        } else {
          ng = k;
        }
      }

      int y = a[i] > 0 ? (ok - i) : (n - ok);
      ret += y;
    }
    return ret;
  }

  public static int lowerBound(int[] a, int v) {
    int low = -1, high = a.length;
    while (high - low > 1) {
      int h = high + low >>> 1;
      if (a[h] >= v) {
        high = h;
      } else {
        low = h;
      }
    }
    return high;
  }

  public static void main(String[] args) {
    new Thread(null, new Runnable() {
      @Override
      public void run() {
        long start = System.currentTimeMillis();
        String debug = args.length > 0 ? args[0] : null;
        if (debug != null) {
          try {
            is = java.nio.file.Files.newInputStream(java.nio.file.Paths.get(debug));
          } catch (Exception e) {
            throw new RuntimeException(e);
          }
        }
        reader = new java.io.BufferedReader(new java.io.InputStreamReader(is), 32768);
        solve();
        out.flush();
        tr((System.currentTimeMillis() - start) + "ms");
      }
    }, "", 64000000).start();
  }

  private static java.io.InputStream is = System.in;
  private static java.io.PrintWriter out = new java.io.PrintWriter(System.out);
  private static java.util.StringTokenizer tokenizer = null;
  private static java.io.BufferedReader reader;

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

  private static double nd() {
    return Double.parseDouble(next());
  }

  private static long nl() {
    return Long.parseLong(next());
  }

  private static int[] na(int n) {
    int[] a = new int[n];
    for (int i = 0; i < n; i++)
      a[i] = ni();
    return a;
  }

  private static char[] ns() {
    return next().toCharArray();
  }

  private static long[] nal(int n) {
    long[] a = new long[n];
    for (int i = 0; i < n; i++)
      a[i] = nl();
    return a;
  }

  private static int[][] ntable(int n, int m) {
    int[][] table = new int[n][m];
    for (int i = 0; i < n; i++) {
      for (int j = 0; j < m; j++) {
        table[i][j] = ni();
      }
    }
    return table;
  }

  private static int[][] nlist(int n, int m) {
    int[][] table = new int[m][n];
    for (int i = 0; i < n; i++) {
      for (int j = 0; j < m; j++) {
        table[j][i] = ni();
      }
    }
    return table;
  }

  private static int ni() {
    return Integer.parseInt(next());
  }

  private static void tr(Object... o) {
    if (is != System.in)
      System.out.println(java.util.Arrays.deepToString(o));
  }
}



Measured memory_bytes: 49828