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

typedef long long ll;
typedef long double ld;
typedef pair<ll, ll> ii;
typedef vector<ll> vi;
typedef vector<vi> vvi;
typedef vector<vvi> vvvi;
typedef vector<vvvi> vvvvi;
typedef vector<ii> vii;

#define x first
#define y second
#define pb push_back
#define eb emplace_back
#define all(v) (v).begin(), (v).end()

const ll m = 100;
const ll maxX = 1'000'000'000;
const ll bs = maxX/m + 1;

void run() {
	ll n;
	cin >> n;
	vvvvi X(m, vvvi(m, vvi(m))), Y(m, vvvi(m, vvi(m))), Z(m, vvvi(m, vvi(m)));

    ll x, y, z;
	while (cin >> x >> y >> z) {
		ll xb = x/bs, yb = y/bs, zb = z/bs;
		X[xb][yb][zb].pb(x);
		Y[xb][yb][zb].pb(y);
		Z[xb][yb][zb].pb(z);
	}
	
	ld res = maxX*3+3;
	for (ll i = 0; i < m-1; i++) {
		for (ll j = 0; j < m-1; j++) {
			for (ll k = 0; k < m-1; k++) {
				vi xs, ys, zs;
				for (ll id = 0; id <= 1; id++) {
					for (ll jd = 0; jd <= 1; jd++) {
						for (ll kd = 0; kd <= 1; kd++) {
							xs.insert(xs.end(), all(X[i+id][j+jd][k+kd]));
							ys.insert(ys.end(), all(Y[i+id][j+jd][k+kd]));
							zs.insert(zs.end(), all(Z[i+id][j+jd][k+kd]));
						}
					}
				}
				for (ll a = 0; a < xs.size(); a++) {
					for (ll b = 0; b < xs.size(); b++) {
						if (a == b) continue;
						res = min(res, sqrt((ld) (xs[a]-xs[b])*(xs[a]-xs[b]) + 
									(ys[a]-ys[b])*(ys[a]-ys[b]) + (zs[a]-zs[b])*(zs[a]-zs[b])));
					}
				}
			}
		}
	}
	cout << res << endl;
}

signed main() {
    ios_base::sync_with_stdio(false); cin.tie(0);
	cout << fixed << setprecision(20);
    run();
    return 0;
}