#include <bits/stdc++.h>
using namespace std;

typedef long long   signed int LL;
typedef long long unsigned int LU;

#define incID(i, l, r) for(int i = (l)    ; i <  (r); i++)
#define incII(i, l, r) for(int i = (l)    ; i <= (r); i++)
#define decID(i, l, r) for(int i = (r) - 1; i >= (l); i--)
#define decII(i, l, r) for(int i = (r)    ; i >= (l); i--)
#define  inc(i, n) incID(i, 0, n)
#define inc1(i, n) incII(i, 1, n)
#define  dec(i, n) decID(i, 0, n)
#define dec1(i, n) decII(i, 1, n)

#define inII(v, l, r) ((l) <= (v) && (v) <= (r))
#define inID(v, l, r) ((l) <= (v) && (v) <  (r))

#define PB push_back
#define EB emplace_back
#define MP make_pair
#define FI first
#define SE second
#define PQ priority_queue

#define  ALL(v)  v.begin(),  v.end()
#define RALL(v) v.rbegin(), v.rend()
#define  FOR(it, v) for(auto it =  v.begin(); it !=  v.end(); ++it)
#define RFOR(it, v) for(auto it = v.rbegin(); it != v.rend(); ++it)

template<typename T> bool   setmin(T & a, T b) { if(b <  a) { a = b; return true; } else { return false; } }
template<typename T> bool   setmax(T & a, T b) { if(b >  a) { a = b; return true; } else { return false; } }
template<typename T> bool setmineq(T & a, T b) { if(b <= a) { a = b; return true; } else { return false; } }
template<typename T> bool setmaxeq(T & a, T b) { if(b >= a) { a = b; return true; } else { return false; } }
template<typename T> T gcd(T a, T b) { return (b == 0 ? a : gcd(b, a % b)); }
template<typename T> T lcm(T a, T b) { return a / gcd(a, b) * b; }

// ---- ----

void mat_inv3(double z[3][3], double x[3][3]) { // z = x ^ -1
	double d =
		+ x[0][0] * x[1][1] * x[2][2]
		+ x[0][1] * x[1][2] * x[2][0]
		+ x[0][2] * x[1][0] * x[2][1]
		- x[0][2] * x[1][1] * x[2][0]
		- x[0][1] * x[1][0] * x[2][2]
		- x[0][0] * x[1][2] * x[2][1]
	;
	// assert(abs(d) > 0.00001);
	
	double y[3][3] = {
		{ x[1][1]*x[2][2] - x[1][2]*x[2][1], x[0][2]*x[2][1] - x[0][1]*x[2][2], x[0][1]*x[1][2] - x[0][2]*x[1][1] },
		{ x[1][2]*x[2][0] - x[1][0]*x[2][2], x[0][0]*x[2][2] - x[0][2]*x[2][0], x[0][2]*x[1][0] - x[0][0]*x[1][2] },
		{ x[1][0]*x[2][1] - x[1][1]*x[2][0], x[0][1]*x[2][0] - x[0][0]*x[2][1], x[0][0]*x[1][1] - x[0][1]*x[1][0] }
	};
	
	inc(i, 3) {
	inc(j, 3) {
		z[i][j] = y[i][j] / d;
	}
	}
}

template<int N> void mat_prod(double a[N][N], double b[N][N], double c[N][N]) { // a = b * c;
	double d[N][N];
	inc(i, N) {
	inc(j, N) {
		d[i][j] = 0;
	}
	}
	
	inc(i, N) {
	inc(j, N) {
	inc(k, N) {
		(d[i][j] += b[i][k] * c[k][j]);
	}
	}
	}
	
	inc(i, N) {
	inc(j, N) {
		a[i][j] = d[i][j];
	}
	}
	
	return;
}

double norm3(double x, double y, double z) {
	return sqrt(x * x + y * y + z * z);
}

double distance_of_triangle_to_point(double p[4][3]) {
	dec(i, 4) {
	inc(j, 3) {
		p[i][j] -= p[0][j];
	}
	}
	
	double a[3][3] = {
		{ p[1][0], p[2][0], p[1][1] * p[2][2] - p[1][2] * p[2][1] },
		{ p[1][1], p[2][1], p[1][2] * p[2][0] - p[1][0] * p[2][2] },
		{ p[1][2], p[2][2], p[1][0] * p[2][1] - p[1][1] * p[2][0] }
	};
	double d[3][3] = {
		{ p[3][0], 0, 0 },
		{ p[3][1], 0, 0 },
		{ p[3][2], 0, 0 }
	};
	
	double b[3][3];
	mat_inv3(b, a);
	mat_prod(b, b, d);
	
	return abs(b[2][0]) * norm3(a[0][2], a[1][2], a[2][2]);
}

// ----

int n;
double p[301][3];

double f(array<int, 4> a) {
	double q[4][3];
	inc(i, 4) {
	inc(j, 3) {
		q[i][j] = p[a[i]][j];
	}
	}
	
	return distance_of_triangle_to_point(q);
}

int main() {
	cin >> n;
	inc(i, n + 1) {
	inc(j, 3) {
		cin >> p[i][j];
	}
	}
	
	double ans = 0.0;
	incII(k, 1, n) {
	incID(j, 1, k) {
	incID(i, 1, j) {
		ans += f({ i, j, k, 0 });
	}
	}
	}
	
	printf("%.12f\n", ans);
	
	return 0;
}