#include <bits/stdc++.h>
using namespace std;
using lint = long long int;
using pint = pair<int, int>;
using plint = pair<lint, lint>;
struct fast_ios { fast_ios(){ cin.tie(0); ios::sync_with_stdio(false); cout << fixed << setprecision(20); }; } fast_ios_;
#define FOR(i, begin, end) for(int i=(begin),i##_end_=(end);i<i##_end_;i++)
#define IFOR(i, begin, end) for(int i=(end)-1,i##_begin_=(begin);i>=i##_begin_;i--)
#define REP(i, n) FOR(i,0,n)
#define IREP(i, n) IFOR(i,0,n)
template<typename T> istream &operator>>(istream &is, vector<T> &vec){ for (auto &v : vec) is >> v; return is; }
template<typename T> ostream &operator<<(ostream &os, const vector<T> &vec){ os << "["; for (auto v : vec) os << v << ","; os << "]"; return os; }
template<typename T> ostream &operator<<(ostream &os, const deque<T> &vec){ os << "deq["; for (auto v : vec) os << v << ","; os << "]"; return os; }
template<typename T> ostream &operator<<(ostream &os, const set<T> &vec){ os << "{"; for (auto v : vec) os << v << ","; os << "}"; return os; }
template<typename T> ostream &operator<<(ostream &os, const unordered_set<T> &vec){ os << "{"; for (auto v : vec) os << v << ","; os << "}"; return os; }
template<typename T> ostream &operator<<(ostream &os, const multiset<T> &vec){ os << "{"; for (auto v : vec) os << v << ","; os << "}"; return os; }
template<typename T> ostream &operator<<(ostream &os, const unordered_multiset<T> &vec){ os << "{"; for (auto v : vec) os << v << ","; os << "}"; return os; }
template<typename T1, typename T2> ostream &operator<<(ostream &os, const pair<T1, T2> &pa){ os << "(" << pa.first << "," << pa.second << ")"; return os; }
template<typename TK, typename TV> ostream &operator<<(ostream &os, const map<TK, TV> &mp){ os << "{"; for (auto v : mp) os << v.first << "=>" << v.second << ","; os << "}"; return os; }
template<typename TK, typename TV> ostream &operator<<(ostream &os, const unordered_map<TK, TV> &mp){ os << "{"; for (auto v : mp) os << v.first << "=>" << v.second << ","; os << "}"; return os; }
template<typename T> void ndarray(vector<T> &vec, int len) { vec.resize(len); }
template<typename T, typename... Args> void ndarray(vector<T> &vec, int len, Args... args) { vec.resize(len); for (auto &v : vec) ndarray(v, args...); }
template<typename T> bool mmax(T &m, const T q) { if (m < q) {m = q; return true;} else return false; }
template<typename T> bool mmin(T &m, const T q) { if (m > q) {m = q; return true;} else return false; }
template<typename T1, typename T2> pair<T1, T2> operator+(const pair<T1, T2> &l, const pair<T1, T2> &r) { return make_pair(l.first + r.first, l.second + r.second); }
template<typename T1, typename T2> pair<T1, T2> operator-(const pair<T1, T2> &l, const pair<T1, T2> &r) { return make_pair(l.first - r.first, l.second - r.second); }
#define dbg(x) cerr << #x << " = " << (x) << " (L" << __LINE__ << ") " << __FILE__ << endl;
#define FI first
#define SE second
#define ALL(x) (x).begin(), (x).end()
#define SZ(x) ((lint)(x).size())
#define POW2(n) (1LL << (n))

vector<vector<double>> D;

constexpr double INF = 1.1e9;

struct UnionFind // UnionFind Tree (0-indexed)
{
    vector<int> par, rank;
    UnionFind(int N) : par(N), rank(N) { REP(i, N) par[i] = i; }
    int find(int x) { return (par[x] == x) ? x : (par[x] = find(par[x])); }
    void unite(int x, int y) {
        x = find(x), y = find(y); if (x == y) return;
        if (rank[x] < rank[y]) par[x] = y; else par[y] = x;
        if (rank[x] == rank[y]) rank[x]++;
    }
    bool same(int x, int y) { return find(x) == find(y); }
};


int main()
{
    int N;
    cin >> N;
    vector<double> x(N), y(N), a(N);
    REP(i, N) cin >> x[i] >> y[i] >> a[i];
    ndarray(D, N, N);
    REP(i, N) REP(j, N)
    {
        double dx = x[j] - x[i];
        double dy = y[j] - y[i];
        D[i][j] = sqrt(dx * dx + dy * dy);
    }

    double lo = 0, hi = *max_element(ALL(a));
    vector<double> mst_weight(1 << N);
    REP(S, 1 << N)
    {
        UnionFind uf(N);
        using P = pair<double, pint>;
        priority_queue<P, vector<P>, greater<P>> pq;
        REP(i, N) REP(j, i) if ((S >> i) & (S >> j) & 1)
        {
            pq.emplace(D[i][j], pint(i, j));
        }
        double edgecost = 0;
        while (!pq.empty())
        {
            P p = pq.top();
            pq.pop();
            int a = p.second.first, b = p.second.second;
            if (uf.same(a, b)) continue;
            uf.unite(a, b);
            edgecost += p.first;
        }
        mst_weight[S] = edgecost;
    }

    while ((hi - lo) > 0.5e-9 and (hi - lo) / hi > 0.5e-9)
    {
        double c = (lo + hi) / 2;
        vector<int> dp(1 << N);
        REP(S, 1 << N)
        {
            double yoyu = 0.0;
            REP(i, N)
            {
                if ((S >> i) & 1) yoyu += a[i] - c;
            }
            if (yoyu >= mst_weight[S]) dp[S] = true;
            for (int T = (S - 1) & S; T > 0; T = (T - 1) & S)
            {
                if (dp[T] and dp[S - T]) dp[S] = true;
            }
        }
        (dp.back() ? lo : hi) = c;
    }
    cout << lo << endl;
}


Measured memory_bytes: 640