#include <bits/stdc++.h>
using namespace std;
#define eps 1e-12
struct point
{
    double x, y;
}a[100010], o;
double r;
double dis(point a, point b)
{
    return sqrt((a.x - b.x) * (a.x - b.x) + (a.y - b.y) * (a.y - b.y));
}
point get_o(point p1, point p2, point p3)
{
    double a1, b1, c1, a2, b2, c2;
    a1 = 2 * (p1.x - p2.x);
    b1 = 2 * (p1.y - p2.y);
    c1 = (p1.x * p1.x - p2.x * p2.x + p1.y * p1.y - p2.y * p2.y);
    a2 = 2 * (p1.x - p3.x);
    b2 = 2 * (p1.y - p3.y);
    c2 = (p1.x * p1.x - p3.x * p3.x + p1.y * p1.y - p3.y * p3.y);
    point ans;
    ans.x = (b2 * c1 - b1 * c2) / (a1 * b2 - b1 * a2);
    ans.y = (c1 * a2 - c2 * a1) / (b1 * a2 - a1 * b2);
    return ans;
}
const int N(5005);
double X[N], Y[N], Z[N];
double xx[3][N], yy[3][N];
int main()
{
    //freopen("1.in","r",stdin);
    int n;
    cin >> n;
    for(int i = 1; i <= n; ++i) cin >> X[i] >> Y[i] >> Z[i];
    for(int i= 1; i <= n; ++i)
    {
        xx[0][i] = X[i], yy[0][i] = Y[i];
        xx[1][i] = X[i], yy[1][i] = Z[i];
        xx[2][i] = Y[i], yy[2][i] = Z[i];
    }
    double ans = 2147483640;
    int T = 3;
    while(T --> 0)
    {
    for (int i = 1; i <= n; ++i)
        a[i].x = xx[T][i], a[i].y = yy[T][i];
    random_shuffle(a + 1, a + n + 1);
    o = a[1], r = 0;
    for (int i = 2; i <= n; ++i)
    {
        if (dis(o, a[i]) - r < eps) 
            continue;
        o.x = (a[1].x + a[i].x) / 2;
        o.y = (a[1].y + a[i].y) / 2;
        r = dis(a[1], a[i]) / 2;
        for (int j = 1; j < i; ++j)
        {
            if (dis(o, a[j]) - r < eps) 
                continue;
            o.x = (a[i].x + a[j].x) / 2;
            o.y = (a[i].y + a[j].y) / 2;
            r = dis(a[i], a[j]) / 2;
            for (int k = 1; k < j; ++k)
            {
                if (dis(o, a[k]) - r < eps)
                    continue;
                o = get_o(a[i], a[j], a[k]);
                r = dis(o, a[i]);
            }
        }
    }
    ans = min(ans, r);
    }
    printf("%.10f\n", ans*2);
    return 0;
}