//

 //by coolxxx

 //#include<bits/stdc++.h>

 #include<iostream>

 #include<algorithm>

 #include<string>

 #include<iomanip>

 #include<map>

 #include<memory.h>

 #include<time.h>

 #include<stdio.h>

 #include<stdlib.h>

 #include<string.h>

 //#include<stdbool.h>

 #include<math.h>

 #define min(a,b) ((a)<(b)?(a):(b))

 #define max(a,b) ((a)>(b)?(a):(b))

 #define abs(a) ((a)>0?(a):(-(a)))

 #define lowbit(a) (a&(-a))

 #define sqr(a) ((a)*(a))

 #define swap(a,b) ((a)^=(b),(b)^=(a),(a)^=(b))

 #define mem(a,b) memset(a,b,sizeof(a))

 #define eps (1e-8)

 #define J 10

 #define mod 1000000007

 #define MAX 0x7f7f7f7f

 #define PI 3.14159265358979323

 #define N 54

 using namespace std;

 typedef long long LL;

 int cas,cass;

 int n,m,lll,ans;

 int a[N][N];

 int f[N][N][N][N];

 int main()

 {

     #ifndef ONLINE_JUDGE

     freopen("1.txt","r",stdin);

 //    freopen("2.txt","w",stdout);

     #endif

     int i,j,k,l;

 //    for(scanf("%d",&cas);cas;cas--)

 //    for(scanf("%d",&cas),cass=1;cass<=cas;cass++)

     while(~scanf("%d",&n))

 //    while(~scanf("%d",&n))

     {

         scanf("%d",&m);

         for(i=;i<=n;i++)

             for(j=;j<=m;j++)

                 scanf("%d",&a[i][j]);

         for(i=;i<=n;i++)

         {

             for(j=;j<=m;j++)

             {

                 for(k=;k<=n;k++)

                 {

                     for(l=;l<=m;l++)

                     {

                         f[i][j][k][l]=max(

                         max(f[i-][j][k-][l],f[i-][j][k][l-]),

                         max(f[i][j-][k-][l],f[i][j-][k][l-]))+a[i][j];

                         if(i!=k || j!=l) f[i][j][k][l]+=a[k][l];

                     }

                 }

             }

         }

         printf("%d\n",f[n][m][n][m]);

     }

     return ;

 }

 /*

 //

 //

 */