#include<iostream>
#include<cstdio>
#include<cstring>
#include<queue>
using namespace std;
const int N=505,M=N*N*10;
const long long INF=4557430888798830399;
int n;
int l[N][N];
struct Edge
{
    int to,next;
    int cost;
    long long flow;
}edge[M*2];
int cur[N],head[N],cnt=1;
int s,t;
void add_edge(int u,int v,int c,int f)
{
    cnt++;
    edge[cnt].to=v;
    edge[cnt].cost=c;
    edge[cnt].flow=f;
    edge[cnt].next=head[u];
    head[u]=cnt;
    return;
}
void add(int u,int v,int c,int f)
{
    add_edge(u,v,c,f);
    add_edge(v,u,-c,0);
    return; 
}
long long dis[N];
bool spfa()
{
    static bool vis[N];
    memset(vis,false,sizeof(vis));
    memset(dis,63,sizeof(dis));
    queue<int>q;
    vis[s]=true;
    dis[s]=0;
    q.push(s);
    while(!q.empty())
    {
        int u=q.front();
        q.pop();
        vis[u]=false;
        for(int i=head[u];i;i=edge[i].next)
        {
            int v=edge[i].to;
            if(edge[i].flow<=0) continue;
            if(dis[v]>dis[u]+edge[i].cost)
            {
                dis[v]=dis[u]+edge[i].cost;
                if(!vis[v])
                {
                    vis[v]=true;
                    q.push(v);
                }
            }
        }
    }
    return dis[t]!=INF;
}
bool book[N];
pair<long long,long long> dfs(int u,long long flow)
{
    if(u==t||flow==0) return make_pair(flow,0);
    book[u]=true;
    long long used=0,res=0;
    for(int &i=cur[u];i;i=edge[i].next)
    {
        int v=edge[i].to;
        if(book[v]||dis[v]!=dis[u]+edge[i].cost||edge[i].flow<=0) continue;
        pair<long long,long long>t=dfs(v,min(flow,edge[i].flow));
        long long now=t.first;
        res+=t.second+now*edge[i].cost;
        flow-=now;
        edge[i].flow-=now;
        edge[i^1].flow+=now;
        used+=now;
        if(flow==0) break;
    }
    book[u]=false;
    return make_pair(used,res);
}
pair<long long,long long> dinic()
{
    long long ans=0,Min=0;
    while(spfa())
    {
        memcpy(cur,head,sizeof(head));
        pair<long long,long long> res=dfs(s,INF);
        ans+=res.first,Min+=res.second;
    }
    return make_pair(ans,Min);
}
int main()
{
    ios::sync_with_stdio(false);
    cin.tie(nullptr),cout.tie(nullptr);
    cin>>n;
    for(int i=1;i<=n;i++)
        for(int j=1;j<=n;j++)
            cin>>l[i][j];
    s=n+1,t=n+2;
    for(int i=2;i<=n;i+=2)
    {
        if(i==n)
        {
            for(int j=1;j<=n;j+=2)
                add(i,j,l[i][j],1);
            add(s,i,0,1);
        }
        else
        {
            for(int j=1;j<=n;j+=2)
                add(i,j,l[i][j],1);
            add(s,i,0,2);
        }
    }
    for(int i=1;i<=n;i+=2)
        add(i,t,0,2);
    long long ans=dinic().second;
    cout<<ans;
    return 0;
}