#include<stdio.h>
#include<stdlib.h>
#include<time.h>
#include<algorithm>
using namespace std;
int r, c;
int map[310][310];
int dyn[310][310];
int psum[310][310];
int E[310][310][310];
void process() {
int i, j, k;
for (i=1;i<=r;i++) for (j=1;j<=c;j++) psum[i][j] = psum[i-1][j]+psum[i][j-1]-psum[i-1][j-1]+map[i][j];
for (i=0;i<=r;i++) for (j=0;j<=c;j++) for (k=0;k<=r;k++) E[i][j][k] = -1000000000;
for (i=1;i<=r;i++) for (j=1;j<=c;j++) {
if (j!=1) for (k=1;k<i;k++) E[i][j][k] = max(E[i][j-1][k],dyn[k][j-1]+psum[k][j-1]-psum[i][j-1]);
dyn[i][j] = psum[i][j];
if (i!=1&&j!=1) for (k=1;k<i;k++) dyn[i][j] = max(dyn[i][j],E[i][j][k]+psum[i][j]-psum[k][j]);
}
printf("%d\n",dyn[r][c]);
}
void input() {
int i, j;
scanf("%d %d",&r,&c);
for (i=1;i<=r;i++) for (j=1;j<=c;j++) scanf("%d",&map[i][j]);
}
int main() {
input();
process();
return 0;
}
