/*最大凸包*/
#include <stdio.h>
#include <string.h>
#include <algorithm>
using namespace std;
const int maxsz = 55;
int m, dp[maxsz][maxsz], ans;
struct Point {
int x, y;
Point ( int xx = 0, int yy = 0 ) : x(xx), y(yy){};
Point operator + (const Point p ) { return Point ( x + p.x, y + p.y ) ; }
Point operator - (const Point p ) { return Point ( x - p.x, y - p.y ) ; }
}point[maxsz], t[maxsz];
int Dot ( Point i, Point j ) {
return i.x * j.x + i.y * j.y;
}
int Cross ( Point i, Point j ) {
return i.x * j.y - i.y * j.x;
}
bool cmp1 ( const Point &i, const Point &j ) {
return i.y == j.y ? i.x < j.x : i.y < j.y;
}
bool cmp2 ( const Point &i, const Point &j ) {
return Cross (i, j) == 0 ? Dot (i, i) < Dot (j, j) : Cross (i, j) > 0;
}
void solve () {
for (int i = 0; i <= m; i++) {
for (int j = i; j <= m; j++)
dp[i][j] = dp[j][i] = 0;
}
for (int i = 2; i <= m; i++) {
for (int j = 1; j < i; j++) {
if (Cross(t[i], t[j]) == 0) continue;
bool emp = 1;// in triangle
for (int k = j + 1; k < i; k++) {
if (Cross(t[k], t[i]) > 0 && Cross (t[j], t[k]) > 0 && Cross (t[i] - t[j], t[k] - t[j]) > 0)
emp = 0;
}
if (!emp) continue;
int area = Cross (t[j], t[i]);
dp[i][j] = area;
if (Cross(t[j], t[j-1])) {//共线
for (int k = 1; k < j; k++) {
if (Cross(t[k] - t[i], t[j] - t[i]) > 0)
dp[i][j] = max(dp[i][j], dp[j][k] + area);
}
}
ans = max(ans, dp[i][j]);
}
}
}
int main () {
int T, n;
scanf("%d", &T);
while (T--) {
scanf("%d", &n);
for (int i = 1; i <= n; i++) scanf("%d%d", &point[i].x, &point[i].y);
sort ( point + 1, point + 1 + n, cmp1);// sort LTL
ans = 0;
for (int i = 1; i <= n-2; i++, m = 0) {
for (int j = i + 1; j <= n; j++) t[++m] = point[j] - point[i];
sort ( t + 1, t + 1 + m, cmp2);// sort angle
solve();
}
printf("%.1lf
", 1.0 * ans / 2);
}
return 0;
}