#include<bits/stdc++.h>
#define long long int
using namespace std;
const int N=1100, M=1e6;
const int dx[4]={0,1,0,-1};
const int dy[4]={1,0,-1,0};
struct edge{int x,y,f,pre;}a[M];int alen,last[N],cur[N];
void ins(int x,int y,int f)
{
    a[++alen]={x,y,f,last[x]};last[x]=alen;
    a[++alen]={y,x,0,last[y]};last[y]=alen;
}
int n,m,st,ed,h[N];
bool bfs()
{
    queue<int> q;q.push(st);
    memset(h,0,sizeof(h));h[st]=1;
    while(!q.empty())
	{
        int x=q.front();q.pop();
        for(int k=last[x];k;k=a[k].pre)if(a[k].f)
		{
            int y=a[k].y;
            if(!h[y])
			{
                h[y]=h[x]+1;
                q.push(y);
            }
        }    
    }
    return h[ed]>0;
}
int ans;
int dinic(int x,int f)
{
    if(x==ed) return f;
    int sx=0;
    for(int k=cur[x];k;k=a[k].pre)if(a[k].f)
	{
        cur[x]=k;
        int y=a[k].y;
        if(h[y]==h[x]+1)
		{
            int sy=dinic(y,min(f-sx,a[k].f));
            a[k].f-=sy,a[k^1].f+=sy;
            sx+=sy;if(sx==f) return f;
        }
    }
    if(sx==0)h[x]=0;
    return sx;
}
int id(int i,int j){return (i-1)*n+j;}
int main()
{
    scanf("%d",&n);
	alen=1;memset(last,0,sizeof(last));
	st=n*n+1,ed=st+1;
	int sum=0;
    for(int i=1,c;i<=n;i++)for(int j=1;j<=n;j++)
	{
        scanf("%d",&c);sum+=c;
        if((i+j)&1)ins(st,id(i,j),c);
        else ins(id(i,j),ed,c);
        
        if((i+j)&1)
        {
        	for(int t=0;t<4;t++)
        	{
        		int xx=i+dx[t],yy=j+dy[t];
        		if(1<=xx&&xx<=n && 1<=yy && yy<=n)ins( id(i,j), id(xx,yy), 1e9);
        	}
        }
    }
    
    ans=0;
    while(bfs())
	{
        memcpy(cur,last,sizeof(cur));
        ans+=dinic(st,1<<30);
    }
    printf("%d\n",sum-ans);
    return 0;
}