#include <bits/stdc++.h>
#pragma GCC optimize("O3,unroll-loops")
#define ll long long
#define endl "\n"
using namespace std;

void solve()
{
    ll n;
    cin >> n;
    ll a[n], b[n], x[n];
    for (ll i = 0; i < n; i++)
        cin >> a[i] >> b[i] >> x[i];
    long double ans = 0, res;
    for (ll a1 = 1; a1 <= 20; a1++)
    for (ll b1 = 1; b1 <= 20; b1++)
    {
        res = 0;
        long double p = 1;
        for (ll i = 0; i < n; i++)
        {
            ll cnt = 0;
            cnt += (a[i] <= a1) + (a[i] <= b1);
            cnt += (b[i] <= a1) + (b[i] <= b1);
            res += x[i] * p * (2 * (cnt / 4.0) - 1);
            p *= cnt / 2.0 - 1;
        }
        ans = max(ans, res - a1 * b1);
    }
    cout << setprecision(10) << fixed << ans << endl;
}

signed main()
{
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    ll t = 1;
    // precomp();
    // cin >> t;
    for (ll i = 1; i <= t; i++)
        solve();
    // cerr << "\nTime elapsed: " << clock() * 1000.0 / CLOCKS_PER_SEC << " ms\n";
}