#include <fstream>
#include <algorithm>
#include <iomanip>

using namespace std;

const int MAX = 305;
const double INF = 1e12;

typedef pair<int, int> PII;

#define x first
#define y second

int N, K, B[MAX][MAX];
double ans = INF, minArea[MAX];
PII V[MAX];


void citire() {
    ifstream in("popandai.in");
    in >> N >> K;
    for(int i = 1; i <= N; i++) {
        in >> V[i].x >> V[i].y;
    } in.close();
}

inline int abs(int A) {
    if(A < 0) return -1 * A;
    return A;
}

inline int getDeterminant(const PII &A, const PII &B, const PII &C) {
    return A.x * B.y + A.y * C.x + B.x * C.y - B.y * C.x - A.y * B.x - A.x * C.y;
}

int getNumberPointsBelow(const int &i, const int &j) {
    int cnt = 0;
    for(int k = i + 1; k < j; k++) {
        if(getDeterminant(V[i], V[j], V[k]) < 0)
            cnt++;
    } return cnt;
}

inline int getTrianglePoints(int i, int j, int k) {
    if(i > j) swap(i, j);
    if(i > k) swap(i, k);
    if(j > k) swap(j, k);
    if(getDeterminant(V[i], V[k], V[j]) < 0)
        return B[i][k] - B[i][j] - B[j][k] - 1;
    return B[i][j] + B[j][k] - B[i][k];
}

void solve() {
    sort(V + 1, V + N + 1);
    for(int i = 1; i < N; i++)
        for(int j = i + 1; j <= N; j++)
            B[i][j] = getNumberPointsBelow(i, j);
    for(int i = 1; i < N; i++)
        for(int j = i + 1; j <= N; j++) {
            for(int k = 0; k <= N + 1; k++)
                minArea[k] = INF;
            for(int k = 1, cnt; k <= N; k++) {
                if(k == i || k == j || getDeterminant(V[i], V[j], V[k]) >= 0) continue;
                minArea[ cnt = getTrianglePoints(i, j, k) ] = min(minArea[cnt], 0.5 * abs(getDeterminant(V[i], V[j], V[k])));
            }
            for(int k = N; k >= 0; k--) minArea[k] = min(minArea[k], minArea[k + 1]);
            for(int k = 1, cnt; k <= N; k++) {
                if(k == i || k == j || getDeterminant(V[i], V[j], V[k]) < 0) continue;
                cnt = max(0, K - getTrianglePoints(i, j, k));
                ans = min(ans, minArea[cnt] + 0.5 * getDeterminant(V[i], V[j], V[k]));
            }
        }
}

void afisare() {
    ofstream out("popandai.out");
    out << fixed << setprecision(1) << ans << "\n";
    out.close();
}

int main() {
    citire();
    solve();
    afisare();
    return 0;
}