C :

#include<stdio.h>
#include<string.h>
#include<stdlib.h>
#include<math.h>
int map[55][56],f[55][55][55][55];
int max(int a,int b)
{
    return a>b?a:b;
}
int main()
{
    int n,m,i,j,k,l;
    scanf("%d%d",&n,&m);
    for(i = 1 ; i <= n ; i++)
        for(j = 1 ; j <= m ; j++)
        {
            scanf("%d",&map[i][j]);
        }
    memset(f,0,sizeof(f));
    for(i = 1; i <= n; i++)
        for(j = 1 ; j <= m ; j++)
            for( k = 1 ; k <= n ;k ++)
                for(l =1 ; l <= m ; l ++)
                {
                    if((i<n||j<m)&&(i<=k)&&j<=l) continue;
                    int sum = 0 ;
                    sum  = max(f[i-1][j][k-1][l],sum);
                    sum  = max(f[i][j-1][k][l-1],sum);
                    if(i-1!=k&&j!=l-1)
                    sum  = max(f[i-1][j][k][l-1],sum);
                    if(i!=k-1&&j-1!=l)
                    sum  = max(f[i][j-1][k-1][l],sum);
                    f[i][j][k][l]= sum + map[i][j]+map[k][l];
                }
                printf("%d\n",f[n][m][n][m]);
    return 0;
}

C++ :

#include<cstdio>
#include<cstring>
#include<algorithm>
using namespace std;
int dp[102][51][51],a[51][51];
int main()
{
    int x,i,j,k,t;
    int n,m;
        scanf("%d %d",&n,&m);
        memset(dp,0,sizeof(dp));
        for(i=1;i<=n;++i)
            for(j=1;j<=m;++j)
                scanf("%d",&a[i][j]);
        for(k=3;k<n+m;k++)
            for(i=1;i<=n;++i)
                for(j=i+1;j<=n;++j)
                {
                    if(k-i<1||k-j<1)
                        break;
                    if(k-i>m||k-j>m)
                        continue;
                    dp[k][i][j] = max(max(dp[k-1][i-1][j],dp[k-1][i-1][j-1]),max(dp[k-1][i][j-1],dp[k-1][i][j]));
                    dp[k][i][j] +=a[i][k-i]+a[j][k-j];
                }
        t=n+m;
        dp[t][n][n] = max(max(dp[t-1][n-1][n],dp[t-1][n-1][n-1]),max(dp[t-1][n][n-1],dp[n-1][n][n]));
        printf("%d\n",dp[t][n][n]);

    return 0;
}

Pascal :

var
  f:array[-50..101,-50..51,-50..51]of longint;
  a:array[-100..100,-100..100]of longint;
  n,i,j,k,m,maxn,s,minn,xxx:longint;
function max(a,b:longint):longint;
 begin
if a>b then max:=a else max:=b
end;
begin
  //assign(input,'message.in');   reset(input);
  //assign9output,'message.out'); rewrite(output);
  readln(n,m);
  for i:=1 to n do
   for j:=1 to m do read(a[i,j]);      fillchar(f,sizeof(f),0);
  xxx:=m+n-2;
  for k:=2 to xxx do
   begin

     for i:=1 to n do
      for j:=i+1 to n do
        begin
          if abs(j-i) > 1 then
           begin
              f[k,i,j]:=max(f[k-1,i,j],f[k-1,i,j-1]);
              f[k,i,j]:=max(f[k,i,j],f[k-1,i-1,j]);
              f[k,i,j]:=max(f[k,i,j],f[k-1,i-1,j-1]);
              inc(f[k,i,j],a[i,k+1-i]+a[j,k+1-j]);
           end else

           begin
             f[k,i,j]:=max(f[k-1,i,j],f[k-1,i-1,j-1]);
             f[k,i,j]:=max(f[k,i,j],f[k-1,i-1,j]);
              inc(f[k,i,j],a[i,k+1-i]+a[j,k+1-j]);
           end;

        end;
   end;
  writeln(f[xxx,n-1,n]);
//  close(input); rewrite(output);
end.