#include "bits/stdc++.h"
//#include "atcoder/all"
using namespace std;
//using namespace atcoder;
//using mint = modint1000000007;
#define endl "\n"
int N;
vector<vector<int>> A(28, vector<int>(28));
map<long long, long long>dp;

long long dfs(long long v) {
	if (dp.count(v)) {
		return dp[v];
	}
	long long ret = -1e18;
	for (long long i = 0; i < N; ++i) {
		if (1 & (v >> i)) {
			for (long long j = i + 1; j < N; ++j) {
				if (1 & (v >> j)) {
					long long next = v;
					next = next & ~(1 << i);
					next = next & ~(1 << j);
					ret = max(ret, dfs(next) + A[i][j]);
				}
			}
			break;
		}
	}
	dp[v] = ret;
	return dp[v];
}
int main() {
	cin >> N;
	for (int i = 0; i < N; ++i) {
		for (int j = 0; j < N; ++j) {
			cin >> A[i][j];
		}
	}
	dp[(long long)0] = (long long)0;
	cout << dfs((1 << N) - 1) << endl;
	return 0;
}