#include <queue>
#include <cstdio>
#include <cstring>
#include <iostream>
#include <algorithm>
#define ll long long
#define N 80010
#define M 110

using namespace std;
const int inf = 0x3f3f3f3f;
int n, m, s, t, ans;
int dd[M][M], head[N], add_edge, dis[N], now[N];
int u[] = {0, 0, 0, 1, -1}, v[] = {0, 1, -1, 0, 0};
struct node {
	int next, to, val;
}edge[N];

int read() {
	int s = 0, f = 0; char ch = getchar();
	while (!isdigit(ch)) f |= (ch == '-'), ch = getchar();
	while (isdigit(ch)) s = s * 10 + (ch ^ 48), ch = getchar();
	return f ? -s : s;
}

void add(int from, int to, int dis) {
	edge[++add_edge].next = head[from];
	edge[add_edge].to = to;
	edge[add_edge].val = dis;
	head[from] = add_edge;
}

void link() {
	for (int i = 1; i <= n; i++)
		for (int j = 1; j <= m; j++) {
			int pb = (i - 1) * m + j;
			if ((i + j) % 2 == 0) {
				add(s, pb, dd[i][j]);
				add(pb, s, 0);
				for (int k = 1; k <= 4; k++) {
					int x = i + u[k], y = j + v[k];
					int pa = (x - 1) * m + y;
					if (x >= 1 && x <= n && y >= 1 && y <= m) {
						add(pb, pa, inf);
						add(pa, pb, 0);
					}
				}
			} else {
				add(pb, t, dd[i][j]);
				add(t, pb, 0);
			}
		}
}

int bfs() {
	for (int i = s; i <= t; i++) dis[i] = inf;
	queue<int> q; q.push(s), dis[s] = 1, now[s] = head[s]; 
	while (!q.empty()) {
		int x = q.front(); q.pop();
		for (int i = head[x]; i; i = edge[i].next) {
			int to = edge[i].to;
			if (edge[i].val > 0 && dis[to] == inf) {
				q.push(to);	
				now[to] = head[to];
				dis[to] = dis[x] + 1;
				if (to == t) return 1;
			}
		}
	}
	return 0;
}

int dfs(int x, int sum) {
	if (x == t) return sum;
	int k, res = 0;
	for (int i = now[x]; i && sum; i = edge[i].next) {
		now[x] = i;
		int to = edge[i].to;
		if (edge[i].val > 0 && (dis[to] == dis[x] + 1)) {
			k = dfs(to, min(sum, edge[i].val));
			if (!k) dis[to] = inf;
			edge[i].val -= k;
			edge[i ^ 1].val += k;
			res += k, sum -= k;
		}
	}
	return res;
}

int main() {
	n = read(), m = read(), s = 0, t = n * m + 1;
	for (int i = 1; i <= n; i++)
		for (int j = 1; j <= m; j++)
			dd[i][j] = read(), ans += dd[i][j];
	link();
	while (bfs()) 
		ans -= dfs(s, inf);
	cout << ans;
}