#![allow(unused_imports, unused_macros, dead_code)]

macro_rules! min {
    (.. $x:expr) => {{
        let mut it = $x.iter();
        it.next().map(|z| it.fold(z, |x, y| min!(x, y)))
    }};
    ($x:expr) => ($x);
    ($x:expr, $($ys:expr),*) => {{
        let t = min!($($ys),*);
        if $x < t { $x } else { t }
    }}
}
macro_rules! max {
    (.. $x:expr) => {{
        let mut it = $x.iter();
        it.next().map(|z| it.fold(z, |x, y| max!(x, y)))
    }};
    ($x:expr) => ($x);
    ($x:expr, $($ys:expr),*) => {{
        let t = max!($($ys),*);
        if $x > t { $x } else { t }
    }}
}

macro_rules! ewriteln {
    ($($args:expr),*) => { let _ = writeln!(&mut std::io::stderr(), $($args),*); };
}
macro_rules! trace {
    ($x:expr) => { ewriteln!(">>> {} = {:?}", stringify!($x), $x) };
    ($($xs:expr),*) => { trace!(($($xs),*)) }
}
macro_rules! put {
    (.. $x:expr) => {{
        let mut it = $x.iter();
        if let Some(x) = it.next() { print!("{}", x); }
        for x in it { print!(" {}", x); }
        println!("");
    }};
    ($x:expr) => { println!("{}", $x) };
    ($x:expr, $($xs:expr),*) => { print!("{} ", $x); put!($($xs),*) }
}

const M: i64 = 1_000_000_007;

trait Integer {
    fn close(x: Self, y: Self) -> bool;
    fn middle(x: Self, y: Self) -> Self;
}
impl Integer for usize {
    fn close(x: Self, y: Self) -> bool { x + 1 >= y }
    fn middle(x: Self, y: Self) -> Self { (x + y) / 2 }
}
impl Integer for i64 {
    fn close(x: Self, y: Self) -> bool { x + 1 >= y }
    fn middle(x: Self, y: Self) -> Self { (x + y) / 2 }
}
impl Integer for f64 {
    fn close(x: Self, y: Self) -> bool { x + 0.00000001 >= y }
    fn middle(x: Self, y: Self) -> Self { (x + y) / 2.0 }
}

// the most left element in [l, r] such that prop holds
fn binsearch<X: Integer + Copy>(l: X, r: X, prop: &Fn(X) -> bool) -> X {
    if X::close(l, r) {
        r
    } else {
        let mid = X::middle(l, r);
        if prop(mid) {
            binsearch(l, mid, prop)
        } else {
            binsearch(mid, r, prop)
        }
    }
}

fn count(prod: i64, xs: &Vec<i64>) -> i64 {
    // num of <prod
    let n = xs.len();
    let mut r = 0;
    for i in 0..n-1 {
        let z = xs[i];
        if z == 0 {
            if prod > 0 {
                r += (n - 1 - i) as i64;
            }
        } else if z > 0 {
            if xs[i+1] * z >= prod {
            } else if xs[n-1] * z < prod {
                r += (n - 1 - i) as i64;
            } else {
                r += (binsearch(i+1, n, &|i| xs[i] * z >= prod) - i - 1) as i64;
            }
        } else {
            if xs[i+1] * z < prod {
                r += (n - 1 - i) as i64;
            } else if xs[n-1] * z >= prod {
            } else {
                r += (n - binsearch(i+1, n, &|i| xs[i] * z < prod)) as i64;
            }
        }
    }
    r
}

fn main() {
    let mut sc = Scanner::new();
    let n: usize = sc.cin();
    let k: i64 = sc.cin();
    let mut xs: Vec<i64> = sc.vec(n);
    xs.sort();

    let mut left: i64 = -1000000010 * 1000000010;
    let mut right: i64 = 1000000010 * 1000000010;

    for _ in 0..200 {
        let mid = (left + right) / 2;

        let c = count(mid, &xs);
        // trace!(k);
        // trace!(mid, count(mid, &xs));
        // trace!(mid+1, count(mid+1, &xs));
        let d = count(mid + 1, &xs);
        if c < k && d >= k {
            put!(mid);
            return;
        }
        if d < k {
            left = mid;
        } else {
            right = mid;
        }
    }
}

use std::io::{self, Write};
use std::str::FromStr;
use std::collections::VecDeque;

struct Scanner { stdin: io::Stdin, buffer: VecDeque<String>, }
impl Scanner {
    fn new() -> Self { Scanner { stdin: io::stdin(), buffer: VecDeque::new() } }
    fn cin<T: FromStr>(&mut self) -> T {
        while self.buffer.len() == 0 {
            let mut line = String::new();
            let _ = self.stdin.read_line(&mut line);
            for w in line.split_whitespace() {
                self.buffer.push_back(String::from(w));
            }
        }
        self.buffer.pop_front().unwrap().parse::<T>().ok().unwrap()
    }
    fn chars(&mut self) -> Vec<char> { self.cin::<String>().chars().collect() }
    fn vec<T: FromStr>(&mut self, n: usize) -> Vec<T> { (0..n).map(|_| self.cin()).collect() }
}


Measured memory_bytes: 17968