def Cross_Product(P0,P1,P2):
    x0,y0=P0
    x1,y1=P1
    x2,y2=P2
    return (x1-x0)*(y2-y0)-(x2-x0)*(y1-y0)
def Convex_Hull(points,upper_lower=False):
    sorted_points=sorted(points,reverse=True)
    upper_convex_hull=[]
    lower_convex_hull=[]
    for x,y in sorted_points:
        if not upper_convex_hull or upper_convex_hull[-1]!=(x,y):
            while len(upper_convex_hull)>=2 and Cross_Product(upper_convex_hull[-2],(x,y),upper_convex_hull[-1])>=0:
                upper_convex_hull.pop()
            upper_convex_hull.append((x,y))
        if not lower_convex_hull or lower_convex_hull[-1]!=(x,y):
            while len(lower_convex_hull)>=2 and Cross_Product(lower_convex_hull[-2],lower_convex_hull[-1],(x,y))>=0:
                lower_convex_hull.pop()
            lower_convex_hull.append((x,y))
    if upper_lower:
        return upper_convex_hull,lower_convex_hull
    else:
        retu=[]
        for x,y in upper_convex_hull+lower_convex_hull[::-1]:
            if not retu or retu[-1]!=(x,y) and retu[0]!=(x,y):
                retu.append((x,y))
        return retu

T=int(input())
for t in range(T):
    N=int(input())
    X,Y=[],[]
    XY=[]
    for i in range(N):
        x,y=map(int,input().split())
        X.append(x)
        Y.append(y)
        XY.append((x,y))
    P=Convex_Hull(XY)
    le=len(P)
    if le>=4:
        def S(i,j,k):
            return abs(Cross_Product(P[i%le],P[j%le],P[k%le]))
        ans=0
        for a in range(le):
            b,d=a,a
            for c in range(a+2,a+le-1):
                while b<=a:
                    b+=1
                while d<=c:
                    d+=1
                while b+1<c and S(a,b,c)<=S(a,b+1,c):
                    b+=1
                while d+1<a+le and S(a,c,d)<=S(a,c,d+1):
                    d+=1
                ans=max(ans,S(a,b,c)+S(a,c,d))
    elif le==3:
        def S(i,j,k):
            return abs(Cross_Product(XY[i],XY[j],XY[k]))
        ans=0
        a,b,c=[XY.index(p) for p in P]
        for i in range(N):
            if i in (a,b,c):
                continue
            ans=max(ans,S(a,b,c)-S(a,b,i))
            ans=max(ans,S(a,b,c)-S(b,c,i))
            ans=max(ans,S(a,b,c)-S(a,c,i))
    else:
        ans=0
    if ans%2:
        ans=str(ans//2)+".5"
    else:
        ans//=2
    print(ans)