#include <fstream>
#include <algorithm>
#define x first
#define y second

using namespace std;

const char iname[] = "popandai.in";
const char oname[] = "popandai.out";
const int maxn = 305;
const int inf = 2000000000;

ifstream f(iname);
ofstream g(oname);

int under[maxn][maxn], n, p, i, j, k, rez, half[2][maxn], zone, r;

pair<int, int> a[maxn];

int mod(int a) {
	if (a < 0)
		return -a;
	return a;
}

int area(pair<int, int> a, pair<int, int> b, pair<int, int> c) {
	return a.x * (b.y - c.y) + b.x * (c.y - a.y) + c.x * (a.y - b.y);
}

int points_inside(int p, int q, int r) {
	if (a[r] < a[p]) {
		int aux = p;
		p = r;
		r = q;
		q = aux;
	}
	else
		if (a[r] < a[q]) {
			int aux = q;
			q = r;
			r = aux;
		}

	return mod(under[p][q] + under[q][r] - under[p][r]) - ((area(a[p], a[r], a[q]) < 0) && a[r].x != a[q].x) - 2 * (a[p].x == a[q].x);
}

int main() {
	f >> n >> p;
	for (i = 0; i < n; ++i)
		f >> a[i].x >> a[i].y;

	sort(a, a + n);
	for (i = 0; i < n; ++i)
		for (j = i + 1; j < n; ++j)
			for (k = 0; k < n; ++k)
				if (k != i && k != j && a[i].x <= a[k].x && a[k].x < a[j].x)
					if (area(a[i], a[j], a[k]) < 0)
						++under[i][j], ++under[j][i];

	rez = inf;
	for (i = 0; i < n; ++i)
		for (j = i + 1; j < n; ++j) {
			for (k = 0; k < n; ++k)
				half[0][k] = half[1][k] = inf;
			for (k = 0; k < n; ++k)
				if (k != i && k != j) {
					zone = (int)(area(a[i], a[j], a[k]) < 0);
					r = points_inside(i, j, k);
					half[zone][r] = min(half[zone][r], mod(area(a[i], a[j], a[k])));
             }

            for (k = n - 2; k >= 0; --k) {
				half[0][k] = min(half[0][k], half[0][k + 1]);
				half[1][k] = min(half[1][k], half[1][k + 1]);
			}

			for(k = 0; k <= p; ++k)
				if (half[0][k] != inf && half[1][p - k] != inf)
                    rez = min(rez, half[0][k] + half[1][p - k]);
		}
	g << rez/2 << "." << (rez % 2) * 5 << "\n";
}