#include <cstdio>#include <cstring>#include <cmath>#include <string>#include <iostream>#include <algorithm>using namespace std;#define rep(i, n) for(int i=0; i<(n); ++i)#define for1(i,a,n) for(int i=(a);i<=(n);++i)#define for2(i,a,n) for(int i=(a);i<(n);++i)#define for3(i,a,n) for(int i=(a);i>=(n);--i)#define for4(i,a,n) for(int i=(a);i>(n);--i)#define CC(i,a) memset(i,a,sizeof(i))#define max(a,b) ((a)>(b)?(a):(b))#define min(a,b) ((a)<(b)?(a):(b))#define read(a) a=getnum()#define print(a) printf("%d", a)inline int getnum() { int ret=0; char c; for(c=getchar(); c<‘0‘ || c>‘9‘; c=getchar()); for(; c>=‘0‘ && c<=‘9‘; c=getchar()) ret=ret*10+c-‘0‘; return ret; }const int N=40005, M=N*4*2, oo=~0u>>2;int ihead[N], inext[M], from[M], to[M], cap[M], cnt=1;int gap[N], d[N], cur[N], p[N];inline void add(const int &u, const int &v, const int &w) {	inext[++cnt]=ihead[u]; ihead[u]=cnt; from[cnt]=u; to[cnt]=v; cap[cnt]=w;	inext[++cnt]=ihead[v]; ihead[v]=cnt; from[cnt]=v; to[cnt]=u; cap[cnt]=0;}inline int isap(const int &s, const int &t, const int &n) {	int u=s, f, i, flow=0;	for1(i, 0, n) cur[i]=ihead[i];	gap[0]=n;	while(d[s]<n) {		for(i=cur[u]; i; i=inext[i]) if(cap[i] && d[u]==d[to[i]]+1) break;		if(i) {			cur[u]=i; p[to[i]]=i; u=to[i];			if(u==t) {				for(f=oo; u!=s; u=from[p[u]]) f=min(f, cap[p[u]]);				for(u=t; u!=s; u=from[p[u]]) cap[p[u]]-=f, cap[p[u]^1]+=f;				flow+=f;			}		}		else {			if(!(--gap[d[u]])) break;			d[u]=n;			cur[u]=ihead[u];			for(i=ihead[u]; i; i=inext[i]) if(cap[i] && d[u]>d[to[i]]+1) 				d[u]=d[to[i]]+1;			++gap[d[u]];			if(u!=s) u=from[p[u]];		}	}	return flow;}int main() {	int t, u, n;	read(n);	int S=0, T=n*n+1;	int sum=0, last;	for1(i, 1, n) {		last=i;		for1(j, 1, n) {			read(t); sum+=t;			u=(i-1)*n+j;			if(last%2) {				if(i>1) add(u, u-n, oo);				if(i<n) add(u, u+n, oo);				if(j>1) add(u, u-1, oo);				if(j<n) add(u, u+1, oo);				add(S, u, t);			}			else add(u, T, t);			++last;		}	}	printf("%d\n", sum-isap(S, T, T+1));		return 0;}