#include<stdio.h>
#include<queue>
#include<string.h>
using namespace std;
#define inf 0x7fffffff
struct node{
int u,v,w,f,next;
}bian[20000];
int dis[6000],pre[6000],head[6000],visit[6000],yong,minf;
void build(int u,int v,int w,int f) {
bian[yong].u=u;
bian[yong].v=v;
bian[yong].w=w;
bian[yong].f=f;
bian[yong].next=head[u];
head[u]=yong++;
}
void adde(int u,int v,int w,int f) {
build(u,v,w,f);
build(v,u,-w,0);
}
int spfa(int s,int t) {
memset(visit,0,sizeof(visit));
memset(pre,-1,sizeof(pre));
for(int i=0;i<=t;i++)//注意是从0开始而不是从s开始
dis[i]=inf;
queue<int>q;
visit[s]=1;//必须是s
q.push(s);
dis[s]=0;
while(!q.empty ()) {
int u=q.front ();
for(int index=head[u];index!=-1;index=bian[index].next) {
int v=bian[index].v;
if(bian[index].f&&dis[v]>dis[u]+bian[index].w) {
dis[v]=dis[u]+bian[index].w;
pre[v]=index;
if(!visit[v]) {
visit[v]=1;
q.push (v);
}
}
}
q.pop();
visit[u]=0;//是u
}
if(dis[t]==inf)
return 0;
return 1;
}
void addf(int s,int t ) {
int i=pre[t];
int j;
while(i!=-1) {
j=i^1;
bian[i].f--;
bian[j].f++;
minf+=bian[i].w;
i=pre[bian[i].u];//前一个u
}
}
int main() {
int n,k,map[60][60];
while(scanf("%d",&n)!=EOF) {
memset(head,-1,sizeof(head));
k=2;
yong=0;
int s=2*n*n;
int t=s+1;
int i,j;
for(i=0;i<n;i++)
for(j=0;j<n;j++)
scanf("%d",&map[i][j]);
for(i=0;i<n;i++)
for(j=0;j<n;j++) {
int b=i*n+j;
adde(2*b,2*b+1,-map[i][j],1);
adde(2*b,2*b+1,0,k-1);
}
for(i=0;i<n;i++)
for(j=0;j<n-1;j++) {
int b=i*n+j;
adde(2*b+1,2*(b+1),0,k);
}
for(i=0;i<n-1;i++)
for(j=0;j<n;j++) {
int b=i*n+j;
adde(2*b+1,2*(b+n),0,k);
}
adde(s,0,0,k);
adde(2*n*n-1,t,0,k);
minf=0;
while(spfa(s,t)) {
addf(s,t);
}
printf("%d\n",-minf);
}
return 0;
}