import std.stdio, std.string, std.conv, std.range;
import std.algorithm, std.array, std.typecons, std.container;
import std.math, std.numeric, std.random, core.bitop;

enum inf = 1_001_001_001;
enum infl = 1_001_001_001_001_001_001L;
enum mod = 1_000_000_007L;


void main() {
    int N; long K;
    scan(N, K);
    auto a = readln.split.to!(long[]);

    long[] neg, pos;
    long zero;

    foreach (ai ; a) {
        if (ai < 0) neg ~= ai;
        else if (ai > 0) pos ~= ai;
        else zero++;
    }

    auto ns = neg.sort!"a > b"();
    auto ps = pos.sort();

    auto pn = ps.length.to!int;
    auto nn = ns.length.to!int;

    bool check(long x) {
        long cnt;

        if (x >= 0) {
            int r;
            foreach_reverse (i ; 0 .. pn) {
                while (r < pn && ps[i] * ps[r] <= x) {
                    r++;
                }
                cnt += r;
                if (i < r) cnt -= (r - i);
            }
            r = 0;
            foreach_reverse (i ; 0 .. nn) {
                while (r < nn && ns[i] * ns[r] <= x) {
                    r++;
                }
                cnt += r;
                if (i < r) cnt -= (r - i);
            }
            cnt += (zero - 1) * zero / 2 + zero * (N - zero);
            cnt += 1L * pn * nn;
        }
        else {
            int l = pn - 1;
            foreach (i ; 0 .. nn) {
                while (l >= 0 && ns[i] * ps[l] <= x) {
                    l--;
                }
                cnt += pn - 1 - l;
            }
        }

        debug {
            writefln("x: %s, cnt: %s", x, cnt);
        }

        return cnt >= K;
    }

    long ng = -infl, ok = infl;

    while (abs(ok - ng) > 1) {
        auto mid = (ok + ng) / 2;
        (check(mid) ? ok : ng) = mid;
    }

    writeln(ok);
}



void scan(T...)(ref T args) {
    import std.stdio : readln;
    import std.algorithm : splitter;
    import std.conv : to;
    import std.range.primitives;

    auto line = readln().splitter();
    foreach (ref arg; args) {
        arg = line.front.to!(typeof(arg));
        line.popFront();
    }
    assert(line.empty);
}

void fillAll(R, T)(ref R arr, T value) {
    static if (is(typeof(arr[] = value))) {
        arr[] = value;
    }
    else {
        foreach (ref e; arr) {
            fillAll(e, value);
        }
    }
}

bool chmin(T, U...)(ref T x, U args) {
    bool isChanged;

    foreach (arg; args) {
        if (x > arg) {
            x = arg;
            isChanged = true;
        }
    }

    return isChanged;
}

bool chmax(T, U...)(ref T x, U args) {
    bool isChanged;

    foreach (arg; args) {
        if (x < arg) {
            x = arg;
            isChanged = true;
        }
    }

    return isChanged;
}
