#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;

int N;
int cost[30][30];

int dp[1<<25];


int main(){
  cin >> N;
  rep(i,N){
    rep(j,N){
      cin >> cost[i][j];
    }
  }

  rep(i,1<<25) dp[i] = -1;
  dp[0] = 0;

  rep(i,1<<N){
    if(dp[i] < 0) continue;

    rep(j,N) if(((i>>j)&1) == 0){
      REP(k,j+1,N) if(((i>>k)&1) == 0){
        int ii = i | (1<<j) | (1<<k);
        dp[ii] = max(dp[ii], cost[j][k] + dp[i]);
      }
      break;
    }
  }
  cout << dp[(1<<N)-1] << endl;
  return 0;
}