#include <bits/stdc++.h>
#define ADD(a, b) a = (a + ll(b)) % mod
#define MUL(a, b) a = (a * ll(b)) % mod
#define MAX(a, b) a = max(a, b)
#define MIN(a, b) a = min(a, b)
#define rep(i, a, b) for(int i = int(a); i < int(b); i++)
#define rer(i, a, b) for(int i = int(a) - 1; i >= int(b); i--)
#define all(a) (a).begin(), (a).end()
#define sz(v) (int)(v).size()
#define pb push_back
#define sec second
#define fst first
#define debug(fmt, ...) Debug(__LINE__, ":", fmt, ##__VA_ARGS__)
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
typedef pair<int, int> pi;
typedef pair<ll, ll> pl;
typedef pair<int, pi> ppi;
typedef vector<int> vi;
typedef vector<ll> vl;
typedef vector<vl> mat;
typedef complex<double> comp;
void Debug() {cout << '\n'; }
template<class FIRST, class... REST>void Debug(FIRST arg, REST... rest){
	cout<<arg<<" ";Debug(rest...);}
template<class T>ostream& operator<<(ostream& out,const vector<T>& v) {
	out<<"[";if(!v.empty()){rep(i,0,sz(v)-1)out<<v[i]<<", ";out<<v.back();}out<<"]";return out;}
template<class S, class T>ostream& operator<<(ostream& out,const pair<S, T>& v){
	out<<"("<<v.first<<", "<<v.second<<")";return out;}
const int MAX_N = 200010;
const int MAX_V = 100010;
const double eps = 1e-6;
const ll mod = 1000000007;
const int inf = 1 << 29;
const ll linf = 1LL << 60;
const double PI = 3.14159265358979323846;
///////////////////////////////////////////////////////////////////////////////////////////////////

typedef pair<pi, double> pd;

int N;
double C[(1 << 15)];
double dp[(1 << 15)];

double X[15], Y[15], cap[15];

int par[MAX_N];

int find(int p) {
	if(p == par[p]) return p;
	else return par[p] = find(par[p]);
}

double dist(int a, int b) {
	double dx = X[a] - X[b], dy = Y[a] - Y[b];
	return sqrt(dx * dx + dy * dy);
}

double pre(int bit) {
	vector<pd> e;
	rep(i, 0, N) {
		rep(j, i + 1, N) {
			if(!(bit & (1 << i)) || !(bit & (1 << j))) continue;
			e.pb(make_pair(pi(i, j), dist(i, j)));
		}
	}
	sort(all(e), [](const pd& p1, const pd& p2){return p1.sec < p2.sec;});

	rep(i, 0, N) par[i] = i;
	double res = 0;
	for(auto p : e) {
		int a, b;
		tie(a, b) = p.fst;
		double d = p.sec;
		a = find(a); b = find(b);
		if(a != b) {
			res -= d;
			par[a] = b;
		}
	}

	int cnt = 0;
	rep(i, 0, N) {
		if(!(bit & (1 << i))) continue;
		cnt++;
		res += cap[i];
	}
	return res / cnt;
}

void solve() {
	cin >> N;
	rep(i, 0, N) cin >> X[i] >> Y[i] >> cap[i];
	rep(bit, 1, (1 << N)) {
		C[bit] = pre(bit);
	}
	rep(i, 0, (1 << N)) dp[i] = -inf;

	dp[0] = inf;
	rep(bit, 0, (1 << N)) {
		vector<int> vec;
		rep(i, 0, N) {
			if(!(bit & (1 << i))) vec.pb(i);
		}
		int sn = sz(vec);
		rep(bit2, 1, (1 << sn)) {
			int sbit = 0;
			rep(i, 0, N) {
				if(!(bit2 & (1 << i))) continue;
				sbit |= (1 << vec[i]);
			}
			dp[bit | sbit] = max(dp[bit | sbit], min(dp[bit], C[sbit]));
		}
	}
	cout << dp[(1 << N) - 1] << "\n";
}

int main() {
#ifndef LOCAL
	ios::sync_with_stdio(false);
    cin.tie(0);
#endif
    cout << fixed;
	cout.precision(20);
	srand((unsigned int)time(NULL));
#ifdef LOCAL
	//freopen("in.txt", "wt", stdout); //for tester
    freopen("in.txt", "rt", stdin);
#endif	
	solve();
#ifdef LOCAL
    cerr << "Time elapsed: " << 1.0 * clock() / CLOCKS_PER_SEC << " s.\n";
#endif
	return 0;
}



Measured memory_bytes: 896