#include <cstring>#include <cstdio>#include <cmath>#include <algorithm>using namespace std;#define inf 0x7fffffff#define max(a,b) (a>b?a:b)#define min(a,b) (a<b?a:b)#define eps 1e-7#define MAXV 505//三维点struct pt{    double x, y, z;    pt() {}    pt(double _x, double _y, double _z): x(_x), y(_y), z(_z) {}    pt operator - (const pt p1)    {        return pt(x - p1.x, y - p1.y, z - p1.z);    }    pt operator * (pt p)    {        return pt(y*p.z-z*p.y, z*p.x-x*p.z, x*p.y-y*p.x);    //叉乘    }    double operator ^ (pt p)    {        return x*p.x+y*p.y+z*p.z;    //点乘    }};struct _3DCH{    struct fac    {        int a, b, c;    //表示凸包一个面上三个点的编号        bool ok;        //表示该面是否属于最终凸包中的面    };    int n;    //初始点数    pt P[MAXV];    //初始点    int cnt;    //凸包表面的三角形数    fac F[MAXV*8]; //凸包表面的三角形    int to[MAXV][MAXV];    double vlen(pt a)    {        return sqrt(a.x*a.x+a.y*a.y+a.z*a.z);    //向量长度    }    double area(pt a, pt b, pt c)    {        return vlen((b-a)*(c-a));    //三角形面积*2    }    double volume(pt a, pt b, pt c, pt d)    {        return (b-a)*(c-a)^(d-a);    //四面体有向体积*6    }    //正：点在面同向    double ptof(pt &p, fac &f)    {        pt m = P[f.b]-P[f.a], n = P[f.c]-P[f.a], t = p-P[f.a];        return (m * n) ^ t;    }    void deal(int p, int a, int b)    {        int f = to[a][b];        fac add;        if (F[f].ok)        {            if (ptof(P[p], F[f]) > eps)                dfs(p, f);            else            {                add.a = b, add.b = a, add.c = p, add.ok = 1;                to[p][b] = to[a][p] = to[b][a] = cnt;                F[cnt++] = add;            }        }    }    void dfs(int p, int cur)    {        F[cur].ok = 0;        deal(p, F[cur].b, F[cur].a);        deal(p, F[cur].c, F[cur].b);        deal(p, F[cur].a, F[cur].c);    }    bool same(int s, int t)    {        pt &a = P[F[s].a], &b = P[F[s].b], &c = P[F[s].c];        return fabs(volume(a, b, c, P[F[t].a])) < eps && fabs(volume(a, b, c, P[F[t].b])) < eps && fabs(volume(a, b, c, P[F[t].c])) < eps;    }    //构建三维凸包    void construct()    {        cnt = 0;        if (n < 4)            return;                bool sb = 1;        //使前两点不公点        for (int i = 1; i < n; i++)        {            if (vlen(P[0] - P[i]) > eps)            {                swap(P[1], P[i]);                sb = 0;                break;            }        }        if (sb)return;        sb = 1;        //使前三点不公线        for (int i = 2; i < n; i++)        {            if (vlen((P[0] - P[1]) * (P[1] - P[i])) > eps)            {                swap(P[2], P[i]);                sb = 0;                break;            }        }        if (sb)return;        sb = 1;        //使前四点不共面        for (int i = 3; i < n; i++)        {            if (fabs((P[0] - P[1]) * (P[1] - P[2]) ^ (P[0] - P[i])) > eps)            {                swap(P[3], P[i]);                sb = 0;                break;            }        }        if (sb)return;                fac add;        for (int i = 0; i < 4; i++)        {            add.a = (i+1)%4, add.b = (i+2)%4, add.c = (i+3)%4, add.ok = 1;            if (ptof(P[i], add) > 0)                swap(add.b, add.c);            to[add.a][add.b] = to[add.b][add.c] = to[add.c][add.a] = cnt;            F[cnt++] = add;        }        for (int i = 4; i < n; i++)        {            for (int j = 0; j < cnt; j++)            {                if (F[j].ok && ptof(P[i], F[j]) > eps)                {                    dfs(i, j);                    break;                }            }        }        int tmp = cnt;        cnt = 0;        for (int i = 0; i < tmp; i++)        {            if (F[i].ok)            {                F[cnt++] = F[i];            }        }    }    //表面积    double area()    {        double ret = 0.0;        for (int i = 0; i < cnt; i++)        {            ret += area(P[F[i].a], P[F[i].b], P[F[i].c]);        }        return ret / 2.0;    }    //体积    double volume()    {        pt O(0, 0, 0);        double ret = 0.0;        for (int i = 0; i < cnt; i++)        {            ret += volume(O, P[F[i].a], P[F[i].b], P[F[i].c]);        }        return fabs(ret / 6.0);    }    //表面三角形数    int facetCnt_tri()    {        return cnt;    }    //表面多边形数    int facetCnt()    {        int ans = 0;        for (int i = 0; i < cnt; i++)        {            bool nb = 1;            for (int j = 0; j < i; j++)            {                if (same(i, j))                {                    nb = 0;                    break;                }            }            ans += nb;        }        return ans;    }}hull;int main(){    int i,n;    while(scanf("%d",&hull.n)!=EOF)    {        for(i = 0 ; i < hull.n ;i++)        scanf("%lf%lf%lf",&hull.P[i].x,&hull.P[i].y,&hull.P[i].z);        hull.construct();        printf("%.3f\n",hull.area());    }    return 0;}