#include <fstream>
#include <algorithm>
#include <cstring>
#include <iomanip>
#include <cmath>

using namespace std;

ifstream fin("popandai.in");
ofstream fout("popandai.out");

const long long INF = (1LL << 60);

int N, K;
int sub_dreapta[305][305];
long long under[305], over[305];
long long sol;

struct puncte
{
    int x, y;
};
puncte V[305];

int e_sub_dreapta(puncte A, puncte B, puncte C)
{
    if (A.x > B.x)
        swap(A, B);

    if (1LL * (C.x - A.x) * (B.y - A.y) - 1LL * (C.y - A.y) * (B.x - A.x) > 0LL)
        return 1;
    return 0;
}

void presolve()
{
    for (int i = 1; i <= N; ++i)
        for (int j = i + 1; j <= N; ++j)
            for (int k = 1; k <= N; ++k)
            {
                if (e_sub_dreapta(V[i], V[j], V[k]))
                {
                    if (V[i].x > V[j].x && (V[k].x >= V[j].x && V[k].x < V[i].x))
                    {
                        ++sub_dreapta[i][j];
                        ++sub_dreapta[j][i];
                    }
                    else if (V[i].x < V[j].x && (V[k].x >= V[i].x && V[k].x < V[j].x))
                    {
                        ++sub_dreapta[i][j];
                        ++sub_dreapta[j][i];
                    }
                }
            }
}

int get_nrpct_sub(puncte A, puncte B, puncte C, int i, int j, int k)
{
    // i = A
    // j = B
    // k = C
    if (A.x > B.x)
    {
        swap(A, B);
        swap(i, j);
    }

    if (C.x < A.x)
        return sub_dreapta[k][i] + sub_dreapta[i][j] - sub_dreapta[k][j];
    else if (C.x >= A.x && C.x < B.x)
        return sub_dreapta[i][j] - sub_dreapta[k][i] - sub_dreapta[k][j] - 1;
    //else if (C.x >= B.x)
    return sub_dreapta[i][j] + sub_dreapta[k][j] - sub_dreapta[k][i];
}

int get_nrpct_sus(puncte A, puncte B, puncte C, int i, int j, int k)
{
    if (A.x > B.x)
    {
        swap(A, B);
        swap(i, j);
    }

    if (C.x < A.x)
        return sub_dreapta[k][j] - sub_dreapta[k][i] - sub_dreapta[i][j] - 1;
    else if (C.x >= A.x && C.x < B.x)
        return sub_dreapta[k][i] + sub_dreapta[k][j] - sub_dreapta[i][j];
    //else if (C.x >= B.x)
    if (B.x == C.x)
        return sub_dreapta[k][i] - sub_dreapta[i][j] - sub_dreapta[k][j];
    return sub_dreapta[k][i] - sub_dreapta[i][j] - sub_dreapta[k][j] - 1;
}

long long arie(puncte A, puncte B, puncte C)
{
    return abs(1LL * A.x * B.y + 1LL * B.x * C.y + 1LL * C.x * A.y - 1LL * C.x * B.y - 1LL * A.x * C.y - 1LL * B.x * A.y);
}

void solve()
{
    int p;
    sol = INF;
    for (int i = 1; i <= N; ++i)
        for (int j = i + 1; j <= N; ++j)
        {
            for (int k = 0; k <= N; ++k)
            {
                under[k] = INF;
                over[k] = INF;
            }

            for (int k = 1; k <= N; ++k)
            {
                if ((V[i].x == V[k].x && V[i].y == V[k].y) || (V[j].x == V[k].x && V[j].y == V[k].y))
                    continue;

                if (e_sub_dreapta(V[i], V[j], V[k]))
                {
                    p = get_nrpct_sub(V[i], V[j], V[k], i, j, k);
                    under[p] = min(under[p], arie(V[i], V[j], V[k]));
                }
                else
                {
                    p = get_nrpct_sus(V[i], V[j], V[k], i, j, k);
                    over[p] = min(over[p], arie(V[i], V[j], V[k]));
                }
            }

            for (int k = N - 1; k >= 0; --k)
            {
                under[k] = min(under[k], under[k+ 1]);
                over[k] = min(over[k], over[k + 1]);
            }

            for (int k = 0; k <= K; ++k)
                sol = min(sol, over[k] + under[K - k]);
        }
}

int main()
{
    fin >> N >> K;
    for (int i = 1; i <= N; ++i)
        fin >> V[i].x >> V[i].y;

    presolve();
    solve();

    fout << fixed << setprecision(1) << double(sol) / 2.0;

    fin.close();
    fout.close();
    return 00;
}