#pragma GCC optimize ("O3")
#pragma GCC target ("avx")

#include "bits/stdc++.h"
using namespace std;

typedef long long ll;
typedef unsigned long long ull;
typedef vector<int> veci;
typedef vector<ll> vecll;
typedef vector<string> vecs;
template<class T,class U> using Hash=unordered_map<T,U>;

#define REP(i, a, n) for(ll i = a; i < (ll)n; i++)
#define RREP(i, a, n) for(ll i = n-1; i >= (ll)a; i--)
#define rep(i, n) REP(i, 0, n)
#define rrep(i, n) RREP(i, 0, n)
#define MD 1000000007

template<class T> T read(){T a;cin >> a;return a;}
template<class T> void read(T& a){cin >> a;}
template<class T, class ...Args> void read(T& a, Args&... args){cin >> a; read(args...);} 
template<class T> void rarr(T a, int n){for(int i = 0; i < n; i++) {cin >> a[i];}}
template<char c = ' ',class T> void write(T a){cout << fixed << setprecision(15) << a << endl;}
template<char c = ' ',class T,class ...Args> void write(T a, Args... args){cout << fixed << setprecision(4) << a << c; write<c>(args...);}
template<class T> void warr(vector<T> a, const char* c = " "){cout << a[0];for(int i = 1; i < (int)a.size(); i++)cout << c << a[i];cout << endl;;}
template<class T> void warr(T a, int n, const char* c = " "){cout << a[0];for(int i = 1; i < n; i++)cout << c << a[i];cout << endl;}
void split(string s, string delim, veci& result){result.clear();string::size_type pos = 0;while(pos != string::npos){string::size_type p = s.find(delim, pos);if(p == string::npos){result.push_back(atoi(s.substr(pos).data()));break;}else {result.push_back(atoi(s.substr(pos, p - pos).data()));}pos = p + delim.size();}}
void split(string s, string delim, vecs& result){result.clear();string::size_type pos = 0;while(pos != string::npos){string::size_type p = s.find(delim, pos);if(p == string::npos){result.push_back(s.substr(pos));break;}else {result.push_back(s.substr(pos, p - pos));}pos = p + delim.size();}}
ull gcd(ull a, ull b){while(true){ull k = a % b;if(k == 0)return b;a = b;b = k;}}
ull lcm(ull a, ull b){return a*b/gcd(a,b);}
ull comb(ull n, ull m){ull p=1;m=min(m,n-m);for(ull i=1;i<=m;i++){p*=n-i+1;p/=i;}return p;}

inline int numofbits5(long bits)
{
    bits = (bits & 0x55555555) + (bits >> 1 & 0x55555555);
    bits = (bits & 0x33333333) + (bits >> 2 & 0x33333333);
    bits = (bits & 0x0f0f0f0f) + (bits >> 4 & 0x0f0f0f0f);
    bits = (bits & 0x00ff00ff) + (bits >> 8 & 0x00ff00ff);
    return (bits & 0x0000ffff) + (bits >>16 & 0x0000ffff);
}

inline bool bFlag(int bit,int n){
    return (bit&(1<<n))>0;
}

int dp[1<<24]={0};

int main(void)
{
    clock_t start = clock();    // スタート時間
    
    //vector<int> dp;
    int n,mt[30][30];
    read(n);
    rep(i,n)rep(j,n)read(mt[i][j]);
    int pn=1<<n;
    //dp.resize(pn);
    rep(x,pn){
        int bnum=numofbits5(x);
        if(bnum&1)continue;
        rep(i,n){
            if(x&(1<<i))continue;
            REP(j,i+1,n){
                if(x&(1<<j))continue;
                int nx=x|(1<<i)|(1<<j);
                dp[nx]=max(dp[nx],dp[x]+mt[i][j]);
            }
        }
    }
    write(dp[pn-1]);
    //std::cout << "duration = " << (double)(clock() - start) / CLOCKS_PER_SEC << "sec.\n";
    return 0;
}