#include <bits/stdc++.h>
using namespace std;
#include <atcoder/all>
using namespace atcoder;
#define rep(i, n) for(int i=0;i<(n);++i)
#define rep1(i, n) for(int i=1;i<=(n);i++)
#define ll long long
using mint = modint998244353;
using P = pair<ll,ll>;
using lb = long double;
using T = tuple<ll, ll, ll>;
template<typename T>inline bool chmax(T& a,T b){if(a<b){a=b;return 1;}return 0;}
#ifdef LOCAL
#  include <debug_print.hpp>
#  define dbg(...) debug_print::multi_print(#__VA_ARGS__, __VA_ARGS__)
#else
#  define dbg(...) (static_cast<void>(0))
#endif

int main()
{
    int h, w;
    cin >> h >> w;
    vector<vector<int>> a(h, vector<int>(w));
    rep(i,h)rep(j,w) cin >> a[i][j];
    ll ans = 0;
    vector<pair<int,int>> vs;
    rep(i,w) vs.emplace_back(0,i);
    rep(j,h) vs.emplace_back(j,0);
    rep(i,w) vs.emplace_back(h-1,i);
    rep(i,h) vs.emplace_back(i,w-1);
    sort(vs.begin(),vs.end());
    vs.erase(unique(vs.begin(),vs.end()), vs.end());
    int n = vs.size();
    vector<vector<bool>> used(h, vector<bool>(w));
    rep(i,n){
      rep(j,i+1){
        auto [x_1, y_1] = vs[i];
        auto [x_2, y_2] = vs[j];
        for(int dx=0;dx<=1;dx++){
          for(int dy=-1;dy<=1;dy++){
            if(dx==0 && dy==0) continue;
            for(int ex=0;ex<=1;ex++){
              for(int ey=-1;ey<=1;ey++){
                if(ex==0 && ey==0) continue;
                ll sum = 0;
                int x1 = x_1;
                int y1 = y_1;
                int x2 = x_2;
                int y2 = y_2;
                while(true){
                  if(x1<0 || x1>=h || y1<0 || y1>=w) break;
                  if(!used[x1][y1]) sum += a[x1][y1];
                  used[x1][y1] = true;
                  x1 += dx;
                  y1 += dy;
                }
                while(true){
                  if(x2<0 || x2>=h || y2<0 || y2>=w) break;
                  if(!used[x2][y2]) sum += a[x2][y2];
                  used[x2][y2] = true;
                  x2 += ex;
                  y2 += ey;
                }
                x1 = x_1;
                y1 = y_1;
                x2 = x_2;
                y2 = y_2;
                while(true){
                  if(x1<0 || x1>=h || y1<0 || y1>=w) break;
                  used[x1][y1] = false;
                  x1 += dx;
                  y1 += dy;
                }
                while(true){
                  if(x2<0 || x2>=h || y2<0 || y2>=w) break;
                  used[x2][y2] = false;
                  x2 += ex;
                  y2 += ey;
                }
                ans = max(ans, sum);
              }
            }
          }
        }
      }
    }
    cout << ans << endl;
    return 0;
}