#include <bits/stdc++.h>
using namespace std;
#define REP(i,a,n) for(int i=(a); i<(int)(n); i++)
#define rep(i,n) REP(i,0,n)
#define FOR(it,c) for(__typeof((c).begin()) it=(c).begin(); it!=(c).end(); ++it)
#define ALLOF(c) (c).begin(), (c).end()
typedef long long ll;
typedef unsigned long long ull;

#define INF 100000000
int N;
int cost[30][30];

map<int,int> dp;

int solve(ll S){
  if(S == 0) return 0;
  if(dp.count(S) > 0) return dp[S];
  
  int ret = 0;
  rep(i,N){
    REP(j,i+1,N){
      if(((S>>i)&1) && ((S>>j)&1)){
        ret = max(ret, cost[i][j] + solve(S - (1<<i) - (1<<j)));
      }
    }
  }
  
  return dp[S] = ret;
}


int main(){

  cin >> N;
  rep(i,N){
    rep(j,N){
      cin >> cost[i][j];
      if(i==j) cost[i][j] = -INF;
    }
  }
  cout << solve((1LL<<N)-1) << endl;

  return 0;
}