// codevs1907#include<algorithm>#include<iostream>#include<cstring>#include<cstdlib>#include<cstdio>#include<cmath>#include<queue>#define LL long long#define inf 2147483640#define Pi acos(-1.0)#define free(a) freopen(a".in","r",stdin),freopen(a".out","w",stdout);using namespace std; const int maxn=1000;struct edge {int to,next,w;}e[maxn*100];int head[maxn],d[maxn];int cnt=1,n,m,ans,es,et;void link(int u,int v,int w) {	e[++cnt]=(edge){v,head[u],w};head[u]=cnt;	e[++cnt]=(edge){u,head[v],0};head[v]=cnt;}bool bfs() {	memset(d,-1,sizeof(d));	queue<int> q;q.push(es);d[es]=0;	while (!q.empty()) {		int x=q.front();q.pop();		for (int i=head[x];i;i=e[i].next) if (e[i].w && d[e[i].to]<0) {				d[e[i].to]=d[x]+1;				q.push(e[i].to);			}	}	return d[et]>0;}int dfs(int x,int f) {	if (x==et || f==0) return f;	int w,used=0;	for (int i=head[x];i;i=e[i].next) if (e[i].w && d[e[i].to]==d[x]+1) {			w=dfs(e[i].to,min(e[i].w,f-used));			used+=w;			e[i].w-=w;e[i^1].w+=w;			if (used==f) return used;		}	if (!used) d[x]=-1;	return used;}void Dinic() {	while (bfs()) ans-=dfs(es,inf);}int main() {	scanf("%d%d",&n,&m);	es=n*m+1;et=n*m+2;	for (int i=1;i<=n;i++)		for (int x,j=1;j<=m;j++) {			scanf("%d",&x);			ans+=x;			if ((i+j)%2==1) {link((i-1)*m+j,et,x);continue;}			link(es,(i-1)*m+j,x);			if (i>1) link((i-1)*m+j,(i-2)*m+j,inf);			if (i<n) link((i-1)*m+j,i*m+j,inf);			if (j>1) link((i-1)*m+j,(i-1)*m+j-1,inf);			if (j<m) link((i-1)*m+j,(i-1)*m+j+1,inf);		}	Dinic();	printf("%d",ans);	return 0;}