#include <bits/stdc++.h>   using namespace std;   double dist[5001][5001];   double x[5001], y[5001], z[5001];   int n;   double sqr(double x) { return x * x; }   int main() {     cin >> n;     for (int i = 1; i <= n; i++) cin >> x[i] >> y[i] >> z[i];     for (int i = 1; i <= n; i++) {       for (int j = i + 1; j <= n; j++) {         dist[i][j] = sqrt(sqr(x[i] - x[j]) + sqr(y[i] - y[j]) + sqr(z[i] - z[j]));         dist[j][i] = dist[i][j];       }     }     double distance = 100000;     for (int i = 2; i <= n; i++) {       double minn = 100000;       for (int j = 2; j <= n; j++) {         if (i != j) {           if (dist[1][j] + dist[j][i] < minn) minn = dist[1][j] + dist[j][i];         }       }       if (dist[1][i] + (minn - dist[1][i]) / 2 < distance)         distance = dist[1][i] + (minn - dist[1][i]) / 2;     }     cout.precision(20);     cout << distance;     return 0;   }   