#include <bits/stdc++.h>
using namespace std;
#define ll long long
int32_t main() {
	ios_base::sync_with_stdio(0);
	cin.tie(0);

	int n;
	cin >> n;

	vector <pair <int, double>> v;
    double sum = 0.0;
	for(int i = 0; i < n; i++) {
		int a, b, x;
		cin >> a >> b >> x;
		v.push_back({a, x / 4.0});
        v.push_back({b, x / 4.0});
        sum += x / 2.0;
	}


	sort(v.begin(), v.end());
	

	// if you lose anyways get (1, 1) ?

	double ans = - sum * 2.0 - 1.0;


    n = v.size();

    double cur = 0.0;

    for(int i = 0; i < n; i++) {
        int num = v[i].first;
        double val = v[i].second;
        cur += val;
        // cout << i << " " << cur <<  " " << sum << endl;
        ans = max(ans, 2 * (cur - (sum - cur)) - num * num);
    }

    int j = 0;
    cur = 0.0;
    for(j = 0; j < n; j++) {
        int num = v[j].first;
        double val = v[j].second;
        if(num > 1) break;
        cur += val;
        // cout << i << " " << cur <<  " " << sum << endl;
        ans = max(ans, 2 * (cur - (sum - cur)) - 1);
    }
    double add = cur;
    sum -= cur;
    cur = 0;
    for(; j < n; j++) {
        int num = v[j].first;
        double val = v[j].second;
        cur += val;
        // cout << j << " " << add << " " << num << " " << cur <<  " " << sum - cur << endl;
        ans = max(ans, add * 2 - num - 2 * (sum - cur));
    }


	cout << setprecision(12) << fixed <<  ans << endl;

}