#include<cstdio>
#include<cassert>
#include<cstring>
#include<map>
#include<set>
#include<time.h>
#include<algorithm>
#include<stack>
#include<queue>
#include<utility>
#include<cmath>
#include<iostream>
#include<string>
#include<vector>
using namespace std;
int board[300][300];
bool seen[300][300];
int c[300][300];
int partial[300][300];
int rows, cols;
int psum(int y1, int y2, int x1, int x2) {
int ret = partial[y2][x2];
if(y1) ret -= partial[y1-1][x2];
if(x1) ret -= partial[y2][x1-1];
if(y1 && x1) ret += partial[y1-1][x1-1];
return ret;
}
int go(int y, int x) {
if(y == -1 && x == -1) return 0;
if(y == -1 || x == -1) return -987654321;
int& ret = c[y][x];
if(seen[y][x]) return ret;
seen[y][x] = true;
ret = -987654321;
for(int h = 1; h <= y+1; ++h)
for(int w = 1; w <= x+1; ++w) {
ret = max(ret,
psum(y - h + 1, y, x - w + 1, x) + go(y - h, x - w));
}
// printf("go(%d,%d) = %d\n", y, x, ret);
return ret;
}
int main() {
cin.sync_with_stdio(false);
cin >> rows >> cols;
memset(partial, 0, sizeof(partial));
for(int i = 0; i < rows; ++i) {
for(int j = 0; j < cols; ++j) {
cin >> board[i][j];
partial[i][j] = board[i][j];
if(i > 0) partial[i][j] += partial[i-1][j];
if(j > 0) partial[i][j] += partial[i][j-1];
if(i && j) partial[i][j] -= partial[i-1][j-1];
// printf("%d ", partial[i][j]);
}
// printf("\n");
}
memset(seen, 0, sizeof(seen));
cout << go(rows-1, cols-1) << endl;
}
