#include <cstdio>
#include <cmath>
#include <algorithm>
#define N 200005
 
int n;
long long a[N];
 
inline long long cnt(long long x) {
    long long ans = 0;
    for (int i = 0; i < n; ++i)
        if (!a[i]) ans += x >= 0 ? n - i - 1 : 0;
        else if (a[i] < 0) ans += std::min(n - i - 1, (int)(a + n - std::lower_bound(a, a + n, (long long)std::ceil((long double)x / a[i]))));
        else if (a[i] > 0) ans += std::max(0, (int)(std::upper_bound(a, a + n, (long long)std::floor((long double)x / a[i])) - a - i - 1));
    return ans;
}
 
int main() {
    long long k;
    scanf("%d%lld", &n, &k);
    for (int i = 0; i < n; ++i) scanf("%lld", a + i);
    std::sort(a, a + n);
    long long l = -1e18, r = 1e18;
    while (l < r) {
        long long mid = l + r >> 1;
        if (cnt(mid) < k) l = mid + 1;
        else r = mid;
    }
    printf("%lld\n", l);
    return 0;
}
