#include <cstdio>
#include <cstdlib>
#include <cmath>
#include <cstring>

#include <iostream>
#include <string>
#include <algorithm>
#include <vector>
#include <queue>
#include <stack>
#include <map>
#include <set>

#include <functional>
#include <cassert>

typedef long long ll;
using namespace std;

#define debug(x) cerr << #x << " = " << (x) << endl;


#define mod 1000000007 //1e9+7(prime number)
#define INF 1000000000 //1e9
#define LLINF 2000000000000000000LL //2e18
#define SIZE 30

int dp[1<<24];
int visited[1<<24];
int last[1<<24];
int n;
int f[SIZE][SIZE];

vector<int> vec;
vector<int> vec2[24];

void dfs(int h, int key, int last_){

  last[key] = max(last[key],last_);
  
  if(visited[key]) return;
  visited[key] = true;
  vec2[h].push_back(key);

  if(h >= n-n/4*2){
    vec.push_back(key);
    return;
  }
  
  for(int j=last_;j<n;j++){
    if((1<<j) & key) continue;
    for(int k=j+1;k<n;k++){
      if((1<<k) & key) continue;

      dfs(h+2, key + (1<<j) + (1<<k), j+1);
    }
  }
}

int main(){
  
  scanf("%d",&n);

  for(int i=0;i<n;i++){
    for(int j=0;j<n;j++){
      scanf("%d",f[i]+j);
    }
  }

  dfs(0,0,0);

  for(int i=0;i<=n/4*2;i++){
    for(int t=0;t<vec2[i].size();t++){
      int key = vec2[i][t];
      
      for(int j=last[key];j<n;j++){
        if((1<<j) & key) continue;
        for(int k=j+1;k<n;k++){
          if((1<<k) & key) continue;
          
          int q = key + (1<<j) + (1<<k);
          
          dp[q] = max(dp[q], dp[key] + f[j][k]);
          
        }
      }
    }
  }
  
  int ans = 0;
  
  for(int i=0;i<vec.size();i++){
    int t = vec[i];
    
    ans = max(ans, dp[t] + dp[((1<<n)-1)^(t)]);

  }
   
  printf("%d\n",ans);
  
  return 0;
}