#include <cstdio>
#include <cassert>
#include <cstring>
#include <queue>
#include <algorithm>
#include <cmath>
using namespace std;#define LOOP(i, n) for(int i=1; i<=n; i++)
const int MAX_NODE = 5100, MAX_EDGE = MAX_NODE * 100, INF = 0x3f3f3f3f;struct Dinic
{struct Node;struct Edge;struct Node{Edge *Head, *DfsFrom;int Level;}_nodes[MAX_NODE];int _vCount;Node *Start, *Target;struct Edge{Node *To;Edge *Next, *Rev;int Cap;Edge(Node *to, Edge *next, int cap):To(to),Next(next),Cap(cap){}}*_edges[MAX_EDGE];int _eCount;void Init(int vCount, int sId, int tId){_vCount = vCount;Start = sId + _nodes;Target = tId + _nodes;_eCount = 0;}Edge *AddEdge(Node *from, Node *to, int cap){Edge *e = _edges[++_eCount] = new Edge(to, from->Head, cap);from->Head = e;return e;}void Build(int uId, int vId, int cap){Node *u = uId + _nodes, *v = vId + _nodes;Edge *e1 = AddEdge(u, v, cap), *e2 = AddEdge(v, u, 0);e1->Rev = e2;e2->Rev = e1;}bool Bfs(){static queue<Node*> q;LOOP(i, _vCount)_nodes[i].Level = 0;Start->Level = 1;q.push(Start);while (!q.empty()){Node *u = q.front();q.pop();for (Edge *e = u->Head; e; e = e->Next){if (!e->To->Level && e->Cap){e->To->Level = u->Level + 1;q.push(e->To);}}}return Target->Level;}int Dfs(Node *cur, int limit){if (cur == Target)return limit;if (limit == 0)return 0;int curTake = 0;for (Edge *e = cur->DfsFrom; e; cur->DfsFrom = e = e->Next){if (e->To->Level == cur->Level + 1 && e->Cap){int nextTake = Dfs(e->To, min(limit - curTake, e->Cap));e->Cap -= nextTake;e->Rev->Cap += nextTake;curTake += nextTake;}if (limit - curTake==0)break;}return curTake;}int Proceed(){int ans = 0;while (Bfs()){LOOP(i, _vCount)_nodes[i].DfsFrom = _nodes[i].Head;ans += Dfs(Start, INF);}return ans;}
}g;int main()
{
#ifdef _DEBUGfreopen("c:\\noi\\source\\input.txt", "r", stdin);
#endifconst int direct[][2] = { {-1,0},{0,1},{1,0},{0,-1} };int totCol, totRow, sId, tId, totSum = 0;static int matrix[110*110];scanf("%d%d", &totCol, &totRow);sId = totCol*totRow + 1;tId = totCol*totRow + 2;g.Init(tId, sId, tId);LOOP(col, totCol)LOOP(row, totRow){int cur = (col - 1)*totRow + row;scanf("%d", &matrix[cur]);totSum += matrix[cur];if ((row + col - 1) % 2)g.Build(sId, cur, matrix[cur]);elseg.Build(cur, tId, matrix[cur]);}LOOP(col, totCol)LOOP(row, totRow)if ((row + col -1 ) % 2){int cur = (col - 1)*totRow + row;for (int i = 0; i < 4; i++){int col2 = col + direct[i][0], row2 = row + direct[i][1];if (col2 >= 1 && col2 <= totCol&&row2 >= 1 && row2 <= totRow){int next = totRow*(col2 - 1) + row2;g.Build(cur, totRow*(col2 - 1) + row2, INF);}}}int subt = g.Proceed();printf("%d\n", totSum - subt);return 0;
}