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

const double eps = 1e-8;
int sgn(double x) {
	if (fabs(x) < eps) return 0;
	if (x < 0) return -1;
	else return 1;
}
struct Point3 {
	double x, y, z;
	Point3(double _x = 0, double _y = 0, double _z = 0) 
	{
		x = _x;
		y = _y;
		z = _z;
	}
	void input() { cin >> x >> y >> z; }
	void output() { cout << fixed << setprecision(8) << x << " " << y << " " << z << '\n'; }
	bool operator==(const Point3 &b) const { return sgn(x - b.x) == 0 && sgn(y - b.y) == 0 && sgn(z - b.z) == 0; }
	bool operator<(const Point3 &b) const { return sgn(x - b.x) == 0 ? (sgn(y - b.y) == 0 ? sgn(z - b.z) < 0 : y < b.y) : x < b.x; }

	double len() { return sqrt(x * x + y * y + z * z); }
	double len2() { return x * x + y * y + z * z; }
	double distance(const Point3 &b) const { return sqrt((x - b.x) * (x - b.x) + (y - b.y) * (y - b.y) + (z - b.z) * (z - b.z)); }

	Point3 operator-(const Point3 &b) const { return Point3(x - b.x, y - b.y, z - b.z); }
	Point3 operator+(const Point3 &b) const { return Point3(x + b.x, y + b.y, z + b.z); }
	Point3 operator*(const double &k) const { return Point3(x * k, y * k, z * k); }
	Point3 operator/(const double &k) const { return Point3(x / k, y / k, z / k); }

	// 点乘
	double operator*(const Point3 &b) const { return x * b.x + y * b.y + z * b.z; }
	// 叉乘
	Point3 operator^(const Point3 &b) const { return Point3(y * b.z - z * b.y, z * b.x - x * b.z, x * b.y - y * b.x); }

	double rad(Point3 a, Point3 b)
	{
		Point3 p = (*this);
		return acos(((a - p) * (b - p)) / (a.distance(p) * b.distance(p)));
	}
	// 变换长度
	Point3 trunc(double r)
	{
		double l = len();
		if (!sgn(l)) return *this;
		r /= l;
		return Point3(x * r, y * r, z * r);
	}
};
struct Line3
{
	Point3 s, e;
	Line3() {}
	Line3(Point3 _s, Point3 _e)
	{
		s = _s;
		e = _e;
	}
	bool operator==(const Line3 v) { return (s == v.s) && (e == v.e); }
	void input()
	{
		s.input();
		e.input();
	}
	double length() { return s.distance(e); }
	// 点到直线距离
	double dispointtoline(Point3 p) { return ((e - s) ^ (p - s)).len() / s.distance(e); }
	// 点到线段距离
	double dispointtoseg(Point3 p)
	{
		if (sgn((p - s) * (e - s)) < 0 || sgn((p - e) * (s - e)) < 0)
			return min(p.distance(s), e.distance(p));
		return dispointtoline(p);
	}
	// 返回点p在直线上的投影
	Point3 lineprog(Point3 p)
	{
		return s + (((e - s) * ((e - s) * (p - s))) / ((e - s).len2()));
	}
	// p绕此向量逆时针arg角度
	Point3 rotate(Point3 p, double ang)
	{
		if (sgn(((s - p) ^ (e - p)).len()) == 0) return p;
		Point3 f1 = (e - s) ^ (p - s);
		Point3 f2 = (e - s) ^ (f1);
		double len = ((s - p) ^ (e - p)).len() / s.distance(e);
		f1 = f1.trunc(len);
		f2 = f2.trunc(len);
		Point3 h = p + f2;
		Point3 pp = h + f1;
		return h + ((p - h) * cos(ang)) + ((pp - h) * sin(ang));
	}
	// 点在直线上
	bool pointonseg(Point3 p)
	{
		return sgn(((s - p) ^ (e - p)).len()) == 0 && sgn((s - p) * (e - p)) == 0;
	}
};
struct Plane
{
	Point3 a, b, c, o; // 平面上的三个点，以及法向量
	Plane() {}
	Plane(Point3 _a, Point3 _b, Point3 _c)
	{
		a = _a;
		b = _b;
		c = _c;
		o = pvec();
	}
	Point3 pvec() { return (b - a) ^ (c - a); }
	// ax + by + cz + d = 0
	Plane(double _a, double _b, double _c, double _d)
	{
		o = Point3(_a, _b, _c);
		if (sgn(_a) != 0) a = Point3((-_d - _c - _b) / _a, 1, 1);
		else if (sgn(_b) != 0) a = Point3(1, (-_d - _c - _a) / _b, 1);
		else if (sgn(_c) != 0) a = Point3(1, 1, (-_d - _a - _b) / _c);
	}
	// 点在平面上的判断
	int pointonplane(Point3 p) { return sgn((p - a) * o); }
	// 两平面夹角
	double angleplane(Plane f) { return acos(o * f.o) / (o.len() * f.o.len()); }
	// 平面和直线的交点，返回值是交点个数
	int crossline(Line3 u, Point3 &p)
	{
		double x = o * (u.e - a);
		double y = o * (u.s - a);
		double d = x - y;
		if (sgn(d) == 0) return 0;
		p = ((u.s * x) - (u.e * y)) / d;
		return 1;
	}
	// 点到平面最近点(也就是投影)
	Point3 pointtoplane(Point3 p)
	{
		Line3 u = Line3(p, p + o);
		crossline(u, p);
		return p;
	}
	// 平面和平面的交线
	int crossplane(Plane f, Line3 &u)
	{
		Point3 oo = o ^ f.o;
		Point3 v = o ^ oo;
		double d = fabs(f.o * v);
		if (sgn(d) == 0) return 0;
		Point3 q = a + (v * (f.o * (f.a - a)) / d);
		u = Line3(q, q + oo);
		return 1;
	}
};
Point3 a[60];
int main()
{
	int n;cin>>n;
	double ans=1e18;
	for(int i=1;i<=n;i++) a[i].input();
	for(int i=1;i<=n;i++)
	{
		for(int j=i+1;j<=n;j++)
		{
			for(int k=j+1;k<=n;k++)
			{
				Line3 l={a[i],a[j]};
				if(sgn(l.dispointtoline(a[k]))==0) continue;

				Plane p=Plane(a[i],a[j],a[k]);
				double minn=1e18;
				int f=1;
				for(int o=1;o<=n;o++)
				{
					if(o==i||o==j||o==k) continue;
					int temp=p.pointonplane(a[o]);

					if(o==1) f=temp;
					else if(temp!=0&&f!=temp)
					{
						f=0;
						break;
					}
					
					if(temp==0) continue;
					double dis=a[o].distance(p.pointtoplane(a[o]));

					minn=min(minn,dis);
				}
				
				if(f!=0) ans=min(ans,minn); 
			}
		}
	}
	if(ans>1e16) ans=0;
	cout<<fixed<<setprecision(12)<<ans<<'\n';
}