#include <iostream>
#include <algorithm>
#include <stdio.h>
#include <string.h>
using namespace std;
typedef long long llong;

int n,k;
pair<int,int> pts[52];

pair<int,int> p[52];
int L = 0;

int pivot;

llong dist(llong x,llong y)
{
    return x*x + y*y;
}

llong CP(llong x1,llong y1,llong x2,llong y2)
{
    return x1 * y2 - x2 * y1;
}

llong ABS(llong a)
{
    if (a < 0)
        return -a;
    else
        return a;
}

llong area(pair<int,int> p1,pair<int,int> p2,pair<int,int> p3)
{
    return ABS(CP(p1.first-p3.first,p1.second-p3.second,p2.first-p3.first,p2.second-p3.second));
}

bool SP(pair<int,int> p1,pair<int,int> p2)
{
    llong cval = CP(p1.first - pts[pivot].first, p1.second - pts[pivot].second, p2.first - pts[pivot].first, p2.second - pts[pivot].second);

    if (cval != 0)
        return cval > 0;
    else
        return dist(p1.first - pts[pivot].first, p1.second - pts[pivot].second) > dist(p2.first - pts[pivot].first, p2.second - pts[pivot].second);
}

bool leftTurn(pair<int,int> p1,pair<int,int> p2,pair<int,int> p3)
{
    return CP(p2.first-p1.first,p2.second-p1.second,p3.first-p1.first,p3.second-p1.second) > 0;
}

llong F[52][52][52];

llong solve(int ind1, int ind2, int cnt)
{
    if (cnt < 2)
        return -2LL;
    if (cnt == 2)
    {
        if (ind1 == 1)
            return 0LL;
        else
            return -2LL;
    }
    if (cnt == k)
    {
        if (!leftTurn(p[ind1],p[ind2],p[1]))
            return -2LL;
    }

    if (F[ind1][ind2][cnt] != -1LL)
        return F[ind1][ind2][cnt];

    llong ans = -2LL;
    int i;

    for (i=1;i<ind1;i++)
    {
        if (leftTurn(p[i], p[ind1], p[ind2]))
        {
            llong res = solve(i, ind1, cnt - 1);

            if (res > ans)
                ans = res;
        }
    }

    if (ans != -2LL)
        ans += area(p[ind1], p[ind2], p[1]);

    F[ind1][ind2][cnt] = ans;

    return ans;
}

int main()
{
    freopen("farm.in","r",stdin);
    freopen("farm.out","w",stdout);

    int i,j,in;
    llong ans = -1;
    llong cur;

    scanf("%d %d",&n,&k);

    for (i=1;i<=n;i++)
    {
        scanf("%d %d",&pts[i].first,&pts[i].second);
    }

    for (i=1;i<=n;i++)
    {
        pivot = i;
        L = 0;

        L = 1;
        p[1] = pts[i];

        for (j=1;j<=n;j++)
        {
            if (j == i)
                continue;
            if (pts[j].second < pts[i].second || (pts[j].second == pts[i].second && pts[j].first < pts[i].first))
                continue;

            L++;
            p[L] = pts[j];
        }

        if (L < k)
            continue;

        if (L > 2)
            sort(p+2,p+1+L,SP);

        memset(F,-1,sizeof(F));
        for (j=2;j<=L;j++)
        {
            for (in=1;in<j;in++)
            {
                cur = solve(in, j, k);

                if (cur > ans)
                    ans = cur;
            }
        }
    }

    printf("%lld\n",ans);

    return 0;
}