#include <bits/stdc++.h>   using namespace std;   const int MAXN = 205;   const int MAXM = 55;   struct Point {     int x, y;     double k;     Point(int _x = 0, int _y = 0) { x = _x, y = _y; }     Point operator-(const Point &b) const { return Point(x - b.x, y - b.y); }     bool operator<(const Point &b) const { return k < b.k; }     long long operator*(const Point &b) const {       return 1LL * x * b.y - 1LL * y * b.x;     }   } a[MAXN], p[MAXN];   int n, m;   long long ans, mx[MAXM], f[MAXN][MAXN][MAXM];   vector<int> adj[MAXN], rev[MAXN];   queue<int> q[MAXN];   bool Onleft(Point a, Point b, Point c) { return (b - a) * (c - b) > 0; }   void Add(int x, int y) {     while (!q[x].empty() && Onleft(p[q[x].front()], p[x], p[y]))       Add(q[x].front(), y), q[x].pop();     rev[x].push_back(y);     adj[y].push_back(x);     q[y].push(x);   }   void Init(int n) {     for (int i = 1; i <= n; i++) {       adj[i].clear(), rev[i].clear();       while (!q[i].empty()) q[i].pop();     }     for (int i = 1; i < n; i++) Add(i, i + 1);   }   void Dp(int n) {     memset(f, 0, sizeof(f));     for (int i = n; i; i--) {       for (int j = 0; j < m; j++) mx[j] = 0;       reverse(adj[i].begin(), adj[i].end());       int cur = rev[i].size() - 1;       for (auto j : adj[i]) {         f[j][i][1] = p[j] * p[i];         for (int k = 2; k <= m; k++)           if (mx[k - 1]) f[j][i][k] = mx[k - 1] + p[j] * p[i];         for (; ~cur && Onleft(p[j], p[i], p[rev[i][cur]]); cur--)           for (int k = 1; k < m; k++)             if (mx[k] < f[i][rev[i][cur]][k])               mx[k] = f[i][rev[i][cur]][k], f[j][i][k + 1] = mx[k] + p[j] * p[i];       }     }     for (int i = 1; i <= n; i++)       for (auto j : rev[i]) ans = max(ans, f[i][j][m - 2]);   }   void Solve(int idx) {     int cnt = 0;     for (int i = 1; i <= n; i++)       if (i ^ idx)         if (a[i].x > a[idx].x || (a[i].x == a[idx].x && a[i].y > a[idx].y))           p[++cnt] = a[i] - a[idx], p[cnt].k = atan2(p[cnt].y, p[cnt].x);     sort(p + 1, p + cnt + 1);     Init(cnt);     Dp(cnt);   }   int main() {     scanf( %d%d , &n, &m);     for (int i = 1; i <= n; i++) scanf( %d%d , &a[i].x, &a[i].y);     for (int i = 1; i <= n; i++) Solve(i);     cout << ans / 2 <<  .  << (ans & 1 ?  50  :  00 ) << endl;     return 0;   }   