//#define LOCAL

#include <fstream>
#include <iostream>
#include <cmath>
#include <algorithm>
#include <vector>
#include <map>
#include <queue>
#include <cstring>

#define int long long
//typedef long long ll;
#define rep(i, n) for(int i=0; i<(n); i++)

using namespace std;

int n;
int F[30][30];
int dp[1 << 24];

int rec(int S)
{
    if (dp[S] != -1) return dp[S];

    if (S == 0) return dp[S] =  0;

    int mx = -1;
    for (int i=0; i<(n-1); i++) {
        for (int j=i+1; j<n; j++) {
            if ((S >> i & 1) && (S >> j & 1)) {
                int tempS = S;
                tempS = tempS & ~(1 << i);
                tempS = tempS & ~(1 << j);
                mx = max(mx, rec(tempS) + F[i][j]);
            }
        }
    }

    return dp[S] = mx;
}

signed main()
{
#ifdef LOCAL
    ifstream in("input.txt");
    cin.rdbuf(in.rdbuf());
#endif

    cin >> n;
    rep(i, n) rep(j, n) {
        cin >> F[i][j];
    }

    /*
    rep(i,(1<<(n))) {
        dp[i] = -1;
    }
    */
    memset(dp, -1, sizeof(dp));

    cout << rec((1 << n) - 1) << endl;
}