<?xml version="1.0" encoding="UTF-8"?>

<module type="JAVA_MODULE" version="4">

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<exclude-output />

<content url="file://$MODULE_DIR$">

<sourceFolder url="file://$MODULE_DIR$/src" isTestSource="false" />

</content>

<orderEntry type="inheritedJdk" />

<orderEntry type="sourceFolder" forTests="false" />

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</module>

import java.io.BufferedReader;

import java.io.IOException;

import java.io.InputStreamReader;

import java.util.Deque;

import java.util.LinkedList;

import java.util.StringTokenizer;

public class Main {

static int[] dc = {1, 0, -1, 0};

static int[] dr = {0, 1, 0, -1};

static int[][] paper;

static int maxValue = -(int) 1e9;

static int N;

static int M;

public static void main(String[] args) throws IOException {

BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

StringTokenizer st = new StringTokenizer(br.readLine());

N = Integer.parseInt(st.nextToken());

M = Integer.parseInt(st.nextToken());

paper = new int[N][M];

for (int i = 0; i < N; i++) {

st = new StringTokenizer(br.readLine());

for (int j = 0; j < M; j++) {

paper[i][j] = Integer.parseInt(st.nextToken());

}

}

int[][] visited = new int[N][M];

for (int i = 0; i < N; i++) {

for (int j = 0; j < M; j++) {

visited[i][j] = 1;

findSum(i, j, 1, paper[i][j], visited);

visited[i][j] = 0;

findTsum(i, j);

}

}

System.out.println(maxValue);

}

private static void findTsum(int col, int row) {

int Tvalue = 0;

if (0 <= col - 1 && 0 <= row - 1 && row + 1 < M) { //ㅗ

Tvalue = paper[col - 1][row] + paper[col][row] + paper[col][row + 1] + paper[col][row - 1];

maxValue = Math.max(maxValue, Tvalue);

}

if (col + 1 < N && 0 <= row - 1 && row + 1 < M) { // ㅜ

Tvalue = paper[col + 1][row] + paper[col][row] + paper[col][row + 1] + paper[col][row - 1];

maxValue = Math.max(maxValue, Tvalue);

}

if (0 <= col - 1 && col + 1 < N && row + 1 < M) { //ㅏ

Tvalue = paper[col - 1][row] + paper[col][row] + paper[col][row + 1] + paper[col + 1][row];

maxValue = Math.max(maxValue, Tvalue);

}

if (0 <= col - 1 && col + 1 < N && 0 <= row - 1) { //ㅓ

Tvalue = paper[col - 1][row] + paper[col][row] + paper[col][row - 1] + paper[col + 1][row];

maxValue = Math.max(maxValue, Tvalue);

}

}

private static void findSum(int col, int row, int depth, int total, int[][] visited) {

if (depth == 4) {

maxValue = Math.max(maxValue, total);

return;

}

for (int i = 0; i < 4; i++) {

int cc = dc[i] + col;

int cr = dr[i] + row;

if (0 <= cc && cc < N && 0 <= cr && cr < M) {

if (visited[cc][cr] == 0) {

visited[cc][cr] = 1;

findSum(cc, cr, depth + 1, total + paper[cc][cr], visited);

visited[cc][cr] = 0;

}

}

}

}

}