#include <bits/stdc++.h>

using namespace std;

#define FOR(i, a, b) for(int i = (a); i < (b); i++)
#define RFOR(i, a, b) for(int i = (a) - 1; i >= (b); i--)
#define SZ(a) int(a.size())
#define ALL(a) a.begin(), a.end()
#define PB push_back
#define MP make_pair
#define F first
#define S second

typedef long long LL;
typedef vector<int> VI;
typedef vector<LL> VL;
typedef pair<int, int> PII;
typedef pair<LL, LL> PLL;
typedef double db;

const LL LINF = 1e18;

LL hungarian(const vector<vector<LL>>& a)
{
	int n = SZ(a), m = SZ(a[0]);
	assert(n <= m);
	VL u(n + 1), v(m + 1);
	VI p(m + 1, n), way(m + 1);
	FOR (i, 0, n)
	{
		p[m] = i;
		int j0 = m;
		VL minv(m + 1, LINF);
		VI used(m + 1);
		while (p[j0] != n)
		{
			used[j0] = true;
			int i0 = p[j0], j1 = -1;
			LL delta = LINF;
			FOR (j, 0, m)
			{
				if (!used[j])
				{
					int cur = a[i0][j] - u[i0] - v[j];
					if (cur < minv[j])
					{
						minv[j] = cur;
						way[j] = j0;
					}
					if (minv[j] < delta)
					{
						delta = minv[j];
						j1 = j;
					}
				}
			}
			assert(j1 != -1);
			FOR (j, 0, m + 1)
			{
				if (used[j])
				{
					u[p[j]] += delta;
					v[j] -= delta;
				}
				else
					minv[j] -= delta;
			}
			j0 = j1;
		}
		while (j0 != m)
		{
			int j1 = way[j0];
			p[j0] = p[j1];
			j0 = j1;
		}
	}
	VI ans(n + 1);
	FOR (j, 0, m)
		ans[p[j]] = j;
	LL res = 0;
	FOR (i, 0, n)
		res += a[i][ans[i]];
	assert(res == -v[m]);
	return res;
}

int main()
{
	ios::sync_with_stdio(0);
	cin.tie(0);
	
	int n;
	cin >> n;
	vector<VI> v(n, VI(n));
	FOR (i, 0, n)
		FOR (j, 0, n)
			cin >> v[i][j];
	
	int m = (n + 1) / 2;
	vector<VL> a(m, VL(m));
	FOR (i, 0, n)
	{
		FOR (j, 0, n)
		{
			if (j)
				a[i / 2][j / 2] += 1000ll * v[i][j - 1];
			if (j != n - 1)
				a[i / 2][j / 2] += 1000ll * v[i][j + 1];
			j++;
		}
		i++;
	}
	cout << hungarian(a) / 1000 << '\n';
	
	return 0;
}