#include <cstdio>#include <cstring>#include <iostream>#include <iomanip>#include <algorithm>using namespace std;struct Point{ int x, y; Point() {} Point(int _x, int _y) : x(_x), y(_y) {} inline Point operator + (const Point &o) { return Point(x + o.x, y + o.y); } inline Point operator - (const Point &o) { return Point(x - o.x, y - o.y); } inline int operator * (const Point &o) { return x * o.y - y * o.x; } inline void input() { scanf("%d%d", &x, &y); } inline int norm() { return x * x + y * y; }};const int MAXN = 107;int n;Point src[MAXN];Point dat[MAXN]; inline bool sort_cmp(Point a, Point b){ return a * b > 0 || a * b == 0 && a.norm() < b.norm();}int f[MAXN][MAXN];int Scan(int n){ int result = 0; memset(f, 0, sizeof(f)); for (int i = 1; i < n; i ++) { int j = i - 1; while (j >= 0 && dat[i] * dat[j] == 0) j --; bool flag = j == i - 1; while (j >= 0) { int k = j - 1; while (k >= 0 && (dat[j] - dat[i]) * (dat[k] - dat[j]) > 0) k --; int area = dat[j] * dat[i]; if (k >= 0) area += f[j][k]; if (flag) f[i][j] = area; result = max(result, area); j = k; } if (flag) for (int j = 1; j < i; j ++) f[i][j] = max(f[i][j], f[i][j - 1]); } return result;}int Solve(){ int result = 0; for (int i = 0; i < n; i ++) { int m = 0; for (int j = 0; j < n; j ++) if (src[j].y > src[i].y || (src[j].y == src[i].y && src[j].x > src[i].x)) dat[m ++] = src[j] - src[i]; sort(dat, dat + m, sort_cmp); result = max(result, Scan(m)); } return result;}int main(){ int T; scanf("%d", &T); cout << fixed << setprecision(1); while (T --) { scanf("%d", &n); for (int i = 0; i < n; i ++) src[i].input(); double ans = (double) Solve() / 2.; cout << ans << endl; } return 0;}
