// Author: Expert_Dream
// Copyright (c) 2024 Expert_Dream All rights reserved.
// Problem: P2774 方格取数问题
// Contest: Luogu
// URL: https://www.luogu.com.cn/problem/P2774
// Memory Limit: 125 MB
// Time Limit: 1000 ms
// Date: 2024-05-04 17:21:19

// #pragma GCC optimize(2,3,"Ofast","inline")
#include<bits/stdc++.h>
// #include <atcoder/all>
#define ll long long
#define i128 __int128
#define ull unsigned long long
#define pii pair<int,int>
#define pll pair<long long, long long>
#define fs first
#define sc second
#define x0 _x0_
#define y1 _y1_
#define endl '\n'
#define re register
#define pb push_back
#define vi vector<int>
#define pq priority_queue
#define mem(a,x) memset((a),(x),sizeof(a))
#define debug puts("AK IOI")
#define sz(s) (int)(s.size())
#define all(a) a.begin(),a.end()
#define rd(l,r) (myrand()%(r-l+1)+l)
#define print(x) {cout<<x<<endl;return;}
#define For(x,y,z) for(int x = y;x <= z;x++)
#define For_(x,y,z) for(int x = y;x >= z;x--)
#define between(x, flo, top) (flo <= x && x <= top)
#define id(i, j) ((i - 1) * m + j)
// #define double long double
using namespace std;
// using namespace atcoder;
#define int long long
const int mod = 1e9+7;
//const int mod = 998244353;
mt19937 myrand(time(0));
const int inf = 0x3f3f3f3f,N = 1e4+5,M = 1e6+5,K = 3000+5;
const long long linf = 0x3f3f3f3f3f3f3f3f;
namespace FastIO {template <typename T = int>inline T read() {T s=0,w=1;char c=getchar();while(!isdigit(c)){if(c=='-')w=-1;c=getchar();}while(isdigit(c))s=(s<<1)+(s<<3)+(c^48),c=getchar();return s*w;}template <typename T>inline void read(T &s){s=0;int w=1;char c=getchar();while(!isdigit(c)){if(c=='-')w=-1;c=getchar();}while(isdigit(c))s=(s<<1)+(s<<3)+(c^48),c=getchar();s*=w;}template <typename T, typename... Args> inline void read(T &x, Args &...args) {read(x), read(args...);}template <typename T>inline void write(T x,char ch = '\n') {if(x<0)x=-x,putchar('-');static char stk[200];int top=0;do{stk[top++]=x%10+'0',x/=10;}while(x);while(top)putchar(stk[--top]);putchar(ch);return;}}
using namespace FastIO;
int s,t;
namespace maxflow{
	int dist[N],tot=1,now[N],head[N];
	const int inf = 0x3f3f3f3f3f3f3f3f;
	struct node{
		int to,nxt,val;
	}edge[N];
	void add(int u,int v,int w){
		edge[++tot].to=v,edge[tot].val=w,edge[tot].nxt=head[u],head[u]=tot;
		edge[++tot].to=u,edge[tot].val=0,edge[tot].nxt=head[v],head[v]=tot;//反边
	}bool bfs(){//构建分层图
		memset(dist,0x3f,sizeof dist);
		queue<int> q;q.push(s);dist[s]=0,now[s]=head[s];
		while(!q.empty()){
			int f=q.front();q.pop();
			for(int i=head[f];i;i=edge[i].nxt){
				int to = edge[i].to;
				if(edge[i].val > 0&& dist[to]==inf){
					q.push(to),now[to]=head[to],dist[to]=dist[f]+1;
					if(to==t) return true;//依然可以到达
				}
			}
		}return false;
	}int dfs(int x,int sum){
		if(x==t) return sum;
		int k=0;// 最小剩余容量
		int res=0;
		for(int i = now[x];i && sum;i=edge[i].nxt){
			now[x]=i;// 当前弧优化
			int to = edge[i].to;
			if(edge[i].val && (dist[to] == dist[x] + 1)){
				k=dfs(to,min(sum,edge[i].val));
				if(!k) dist[to] = inf;
				edge[i].val-=k,edge[i^1].val+=k;
				res+=k,sum-=k;
			}
		}return res;
		
	}int dinic(){
		int ans=0;
		while(bfs()) ans += dfs(s,inf);
		return ans;
	}
}using namespace maxflow;
namespace direction{
	int dx[4]={0,0,-1,1},dy[4]={1,-1,0,0}; // 上下左右
	// int dx[4]={1,-1,-1,1},dy[4]={1,-1,1,-1}; // 对角线
	// int dx[8]={0,0,-1,1,1,-1,-1,1},dy[8]={1,-1,0,0,1,-1,1,-1}; // 上下左右 & 对角线
	// int dx[8]={2,1,-1,-2,-2,-1,1,2},dy[8]={1,2,2,1,-1,-2,-2,-1}; // 日字型
}using namespace direction;
int n,m;
int a[N][N];
void solve(){
	int sum=0;
	cin>>n>>m;
	t=n*m+1;
	For(i,1,n)For(j,1,m)cin>>a[i][j];
	For(i,1,n)For(j,1,m){
		sum += a[i][j];
		if(!((i+j)&1)){
			add(s,id(i,j),a[i][j]);
			For(k,0,3){
				int xx=i+dx[k],yy=j+dy[k];
				if(between(xx,1,n) && between(yy,1,m)){
					add(id(i,j),id(xx,yy),linf);
				}
			}
		}else{
			add(id(i,j),t,a[i][j]);
		}
	}
	
	cout<<sum-dinic();
}signed main(){
	solve();
	return 0;
}