#include <bits/stdc++.h>
#define ll long long
#define INF 1000000005
#define MOD 1000000007
#define EPS 1e-10
#define rep(i,n) for(int i=0;i<(int)n;++i)
#define each(a, b) for(auto (a): (b))
#define all(v) (v).begin(),(v).end()
#define fi first
#define se second
#define pb push_back
#define show(x) cout <<#x<<" = "<<(x)<<endl
#define spair(p) cout <<#p<<": "<<p.fi<<" "<<p.se<<endl
#define svec(v) cout<<#v<<":";rep(kbrni,v.size())cout<<" "<<v[kbrni];cout<<endl
#define sset(s) cout<<#s<<":";each(kbrni,s)cout <<" "<<kbrni;cout<<endl

using namespace std;

typedef pair<int,int>P;

const int MAX_N = 24;

int memo[1 << MAX_N];
int fav[MAX_N][MAX_N];
int n;

int rec(int u)
{
    if(memo[u] >= 0){
        return memo[u];
    }
    int f,s;
    int mx = 0;
    int cnt = 0;
    rep(i,n){
        if((u >> i) & 1){
            if(cnt){
                s = i;
                mx = max(mx,rec(u - (1 << f) - (1 << s)) + fav[f][s]);
            }else{
                f = i;
                cnt++;
            }
        }
    }
    memo[u] = mx;
    return mx;
}

int main()
{
    cin >> n;
    rep(i,n){
        rep(j,n){
            cin >> fav[i][j];
        }
    }
    fill(memo,memo+(1<<n),-1);
    cout << rec((1 << n) - 1) << endl;
    return 0;
}