建图方法就是源点连横纵坐标和为奇数的点，横纵坐标之和为偶数的点连汇点，奇数格连偶数格

#include<bits/stdc++.h>
using namespace std;
const int size=1e6+10;
const int inf=0x3f3f3f3f;
int m,n,a[110][110],S,T;
int dx[]={-1,0,1,0};
int dy[]={0,-1,0,1};
inline int encode(int x,int y){return (x-1)*n+y;}
int ver[size],edge[size],nxt[size],head[size],tot=1,d[size],maxflow=0;
inline void add(int x,int y,int z){
	ver[++tot]=y;edge[tot]=z;nxt[tot]=head[x];head[x]=tot;
	ver[++tot]=x;edge[tot]=0;nxt[tot]=head[y];head[y]=tot;
}
inline bool bfs(){
	queue<int> q;
	while(!q.empty()) q.pop();
	memset(d,0,sizeof(d));
	q.push(S);d[S]=1;
	while(!q.empty()){
		int x=q.front();q.pop();
		for(int i=head[x];i;i=nxt[i]){
			int y=ver[i],z=edge[i];
			if(z&&(!d[y])){
				d[y]=d[x]+1;
				q.push(y);
				if(y==T) return 1;
			}
		}
	}
	return 0;
}
int dinic(int x,int flow){
	if(x==T) return flow;
	int used=0;
	for(int i=head[x];i;i=nxt[i]){
		int y=ver[i],z=edge[i];
		if(d[y]==d[x]+1&&z&&used<flow){
			int now=dinic(y,min(flow,z));
			used+=now;
			edge[i]-=now;
			edge[i^1]+=now;
		}
	}
	if(!used) d[x]=0;
	return used;
}
int main(){
	ios::sync_with_stdio(0);
	cin>>m>>n;
	S=0;T=m*n+1;
	for(int i=1;i<=m;++i) for(int j=1;j<=n;++j) cin>>a[i][j];
	for(int i=1;i<=m;++i) for(int j=1;j<=n;++j) ((i+j)%2==0)?add(encode(i,j),T,a[i][j]):add(S,encode(i,j),a[i][j]);
	for(int i=1;i<=m;++i) for(int j=1;j<=n;++j) if((i+j)&1) for(int k=0;k<4;++k) if(i+dx[k]<=m&&i+dx[k]>=1&&j+dy[k]<=n&&j+dy[k]>=1) add(encode(i,j),encode(i+dx[k],j+dy[k]),inf);
	int flow;
	while(bfs()) while(flow=dinic(S,inf)) maxflow+=flow;
	cout<<maxflow<<endl;
	return 0;
}