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

#define SZ(a) (int)a.size()
#define ALL(a) a.begin(), a.end()
#define FOR(i, a, b) for (int i = (a); i<(b); ++i)
#define RFOR(i, b, a) for (int i = (b)-1; i>=(a); --i)
#define MP make_pair
#define PB push_back
#define F first
#define S second
#define FILL(a, b) memset(a, b, sizeof(a))

typedef long long LL;
typedef pair<int, int> PII;
typedef vector<int> VI;

typedef long double db;

const int N = 1 << 17;
const int INF = 1e9;
int x[N][3];

db dist(int i, int j){
	db sum = 0;
	FOR(t, 0, 3){
		db d = x[i][t] - x[j][t];
		sum += d * d;
	}
	return sqrt(sum);
}

db bin_d;
bool OK(int i, int j){
	return dist(i, j) < bin_d;
}

struct Tree{
	set<PII> ys[2 * N];
	
	
	void add(int v, int tl, int tr, int l, int r, int i){
		if(l > r)
			return;
		if(tl == l && tr == r){
			ys[v].insert(MP(x[i][1], i));
			return;
		}
		int tm = (tl + tr) / 2;
		add(2 * v, tl, tm, l, min(r, tm), i);
		add(2 * v + 1, tm + 1, tr, max(tm + 1, l), r, i);
	}
	void rem(int v, int tl, int tr, int l, int r, int i){
		if(l > r)
			return;
		if(tl == l && tr == r){
			ys[v].erase(MP(x[i][1], i));
			return;
		}
		int tm = (tl + tr) / 2;
		rem(2 * v, tl, tm, l, min(r, tm), i);
		rem(2 * v + 1, tm + 1, tr, max(tm + 1, l), r, i);
	}
	
	
	
	bool check(int v, int i, int d){
		auto it = ys[v].lower_bound(MP(x[i][1] - d, -1));
		
		while(it != ys[v].end()){
			if(it->F > x[i][1] + d)
				break;
			
			if(it->S != i && OK(i, it->S))
				return 1;
			it++;
		}
		return 0;
	}
	bool check(int v, int tl, int tr, int pos, int i, int d){
		if(check(v, i, d))
			return 1;
	
		if(tl == tr)
			return 0;
		
		int tm = (tl + tr) / 2;
		if(pos <= tm)
			return check(2 * v, tl, tm, pos, i, d);
		return check(2 * v + 1, tm + 1, tr, pos, i, d);
	}
}T;


bool check(int n, db m){
	bin_d = m;
	FOR(i, 0, n)
	FOR(j, 0, i)
		if(OK(i, j))
			return 1;
	return 0;
	
	int d = int(m) + 1;
	
	vector<PII> events(3 * n);
	FOR(i, 0, n){
		events[3 * i] = MP(x[i][2] - d, i + 1);
		events[3 * i + 1] = MP(x[i][2] + d + 1, -(i + 1));
		events[3 * i + 2] = MP(x[i][2], INF + i);
	}
	sort(ALL(events));
	
	VI xs(n);
	FOR(i, 0, n)
		xs[i] = x[i][0];
	sort(ALL(xs));
	
	
	set<int> idx;
	
	FOR(it, 0, 3 * n){
		int id = events[it].S;
		if(id >= INF){
			//query
			id -= INF;

			
			
			int pos = lower_bound(ALL(xs), x[id][0]) - xs.begin();	
			if(T.check(1, 0, n - 1, pos, id, d))
				return 1;
			
			continue;
		}
		
		int t = (id > 0);
		id = abs(id) - 1;
		
		int lx = lower_bound(ALL(xs), x[id][0] - d) - xs.begin();
		int rx = upper_bound(ALL(xs), x[id][0] + d) - xs.begin() - 1;
		
		
		if(t){
			T.add(1, 0, n - 1, lx, rx, id);
			idx.insert(id);
		}
		else{
			T.rem(1, 0, n - 1, lx, rx, id);
			idx.erase(id);
		}
	}
	return 0;
}



int main()
{
	ios::sync_with_stdio(false);
	cin.tie(0);
	int n;
	cin >> n;
	FOR(i, 0, n)
		FOR(t, 0, 3)
			cin >> x[i][t];
	
	
	
	
	db l = 0, r = 2e9;
	FOR(t, 0, 47){
		db m = bin_d = (l + r) / 2;
		
		if(check(n, m))
			r = m;
		else
			l = m;
	}
	cout << fixed << setprecision(10) << r << endl;
	
	
	
	return 0;
}