#include <cstdio>
#include <algorithm>
using namespace std;
int a[301][301];
int sum[301][301];
int dp[301][301];
int r,c;
int recsum(int x1, int x2, int y1, int y2){
return sum[x2][y2] - sum[x1-1][y2] - sum[x2][y1-1] + sum[x1-1][y1-1];
}
int main(){
scanf("%d %d",&r,&c);
for (int i=1; i<=r; i++) {
for (int j=1; j<=c; j++) {
scanf("%d",&a[i][j]);
}
}
for (int i=1; i<=r; i++) {
for (int j=1; j<=c; j++) {
sum[i][j] = sum[i-1][j] + sum[i][j-1] - sum[i-1][j-1] + a[i][j];
}
}
for (int i=1; i<=r; i++) {
dp[i][1] = sum[i][1];
}
for (int i=1; i<=c; i++) {
dp[1][i] = sum[1][i];
}
for (int i=2; i<=r; i++) {
for (int j=2; j<=c; j++) {
dp[i][j] = sum[i][j];
for (int k=2; k<=i; k++) {
for (int l=2; l<=j; l++) {
dp[i][j] = max(dp[i][j],dp[k-1][l-1] + recsum(k,i,l,j));
}
}
}
}
printf("%d",dp[r][c]);
}
