#include <bits/stdc++.h>

#define _overload(_1,_2,_3,name,...) name
#define _rep(i,n) _range(i,0,n)
#define _range(i,a,b) for(int i=int(a);i<int(b);++i)
#define rep(...) _overload(__VA_ARGS__,_range,_rep,)(__VA_ARGS__)

#define _rrep(i,n) _rrange(i,n,0)
#define _rrange(i,a,b) for(int i=int(a)-1;i>=int(b);--i)
#define rrep(...) _overload(__VA_ARGS__,_rrange,_rrep,)(__VA_ARGS__)

#define _all(arg) begin(arg),end(arg)
#define uniq(arg) sort(_all(arg)),(arg).erase(unique(_all(arg)),end(arg))
#define getidx(ary,key) lower_bound(_all(ary),key)-begin(ary)
#define clr(a,b) memset((a),(b),sizeof(a))
#define bit(n) (1LL<<(n))
#define popcount(n) (__builtin_popcountll(n))

using namespace std;

template<class T>bool chmax(T &a, const T &b) { return (a < b) ? (a = b, 1) : 0;}
template<class T>bool chmin(T &a, const T &b) { return (b < a) ? (a = b, 1) : 0;}

using ll = long long;
using R = long double;
const R EPS = 1e-9L; // [-1000,1000]->EPS=1e-8 [-10000,10000]->EPS=1e-7
inline int sgn(const R& r) {return (r > EPS) - (r < -EPS);}
inline R sq(R x) {return sqrt(max(x, 0.0L));}

const int dx[8] = {1, 0, -1, 0, 1, -1, -1, 1};
const int dy[8] = {0, 1, 0, -1, 1, 1, -1, -1};

// Problem Specific Parameter:
#define error(args...) { vector<string> _debug = split(#args, ',');err(begin(_debug), args);}

vector<string> split(const string& s, char c) {
	vector<string> v; stringstream ss(s); string x;
	while (getline(ss, x, c)) v.emplace_back(x);
	return move(v);
}

void err(vector<string>::iterator it) {cerr << endl;}
template<typename T, typename... Args> void err(vector<string>::iterator it, T a, Args... args) {
	cerr << it -> substr((*it)[0] == ' ', it -> length()) << " = " << a << " ", err(++it, args...);
}


// Description: 素集合を管理するデータ構造
// TimeComplexity: 初期化$\mathcal{O}(n)$ 更新$\mathcal{O}(\log n)$
// Verifyed: AOJ DSL_1_A

struct Union_find {
	Union_find(int n) {data.assign(n, -1);}
	int find(int x) {return (data[x] < 0) ? x : data[x] = find(data[x]);}
	void unite(int a, int b) {
		a = find(a), b = find(b);
		if (a != b) {
			if (data[a] < data[b]) swap(a, b);
			data[a] += data[b], data[b] = a;
		}
	}
	bool same(int a, int b) {return find(a) == find(b);}
	int size(int x) {return -data[x];}
	vector<int> data;
};

int x[15], y[15], a[15];
bool dp[1 << 15];
R cost[1 << 15];

bool check(int n, R val) {
	rep(mask, 1 << n) {
		dp[mask] = false;
		const R m = __builtin_popcountll(mask);
		R cur = 0.0;
		rep(i, n) if (mask & (1 << i)) cur += a[i];
		cur -= cost[mask] + m * val;
		if (cur >= 0.0) dp[mask] = true;
		//error(mask, dp[mask]);
	}

	rep(mask, 1 << n) {
		if (dp[mask]) continue;
		for (int smask = (mask - 1) &mask; ; smask = (smask - 1) & mask) {
			const int tmask = mask ^ smask;
			if (smask < tmask) break;

			if (dp[smask] and dp[tmask]) {
				dp[mask] = true;
				break;
			}
		}
	}

	return dp[(1 << n) - 1];
}

int main(void) {
	int n;
	cin >> n;

	rep(i, n) cin >> x[i] >> y[i] >> a[i];

	using edge = tuple<R, int, int>;
	vector<edge> ary;

	rep(j, n)rep(i, j)  ary.push_back(edge(hypot(x[i] - x[j], y[i] - y[j]), i, j));
	sort(begin(ary), end(ary));

	rep(mask, 1 << n) {
		cost[mask] = 0.0;
		Union_find uf(n);

		for (auto &e : ary) {
			R w;
			int a, b;
			tie(w, a, b) = e;
			if (((mask >> a) & 1) == 0) continue;
			if (((mask >> b) & 1) == 0) continue;
			if (uf.same(a, b)) continue;
			cost[mask] += w;
			uf.unite(a, b);
		}
		//error(mask, cost[mask]);
	}

	R low = 0.0, high = 1e10;

	rep(loop, 100) {
		const R mid = (low + high) / 2.0;
		if (check(n, mid))
			low = mid;
		else
			high = mid;
	}

	cout.precision(20);
	cout << fixed << low << endl;

	/*
	cerr << check(n, 5.5) << endl;
	cerr << check(n, 7.5) << endl;
	*/

	return 0;
}

Measured memory_bytes: 896