#include<bits/stdc++.h>
namespace {
#pragma GCC diagnostic ignored "-Wunused-function"
#include<atcoder/all>
#pragma GCC diagnostic warning "-Wunused-function"
using namespace std;
using namespace atcoder;
#define rep(i,n) for(int i = 0; i < (int)(n); i++)
#define rrep(i,n) for(int i = (int)(n) - 1; i >= 0; i--)
#define all(x) begin(x), end(x)
#define rall(x) rbegin(x), rend(x)
template<class T> bool chmax(T& a, const T& b) { if (a < b) { a = b; return true; } else return false; }
template<class T> bool chmin(T& a, const T& b) { if (b < a) { a = b; return true; } else return false; }
using ll = long long;
using P = pair<int,int>;
using VI = vector<int>;
using VVI = vector<VI>;
using VL = vector<ll>;
using VVL = vector<VL>;

bool used[110][110];

} int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  int n, m;
  cin >> n >> m;
  VVI a(n, VI(m));
  rep(i, n) rep(j, m) cin >> a[i][j];
  vector<vector<P>> ps;
  rep(i, n) {
    vector<P> d;
    rep(j, m) d.emplace_back(i, j);
    ps.emplace_back(move(d));
  }
  rep(j, m) {
    vector<P> d;
    rep(i, n) d.emplace_back(i, j);
    ps.emplace_back(move(d));
  }
  rep(s, n + m - 1) {
    vector<P> d;
    rep(i, n) rep(j, m) if (i + j == s) {
      d.emplace_back(i, j);
    }
    ps.emplace_back(move(d));
  }
  for(int s = -(m-1); s <= n-1; s++) {
    vector<P> d;
    rep(i, n) rep(j, m) if (i - j == s) {
      d.emplace_back(i, j);
    }
    ps.emplace_back(move(d));
  }
  int ans = 0;
  int sz = ps.size();
  VI sm(sz);
  rep(p, sz) {
    for(auto [i, j] : ps[p]) sm[p] += a[i][j];
  }
  rep(p1, ps.size()) {
    for (auto [i, j] : ps[p1]) used[i][j] = true;
    rep(p2, p1) {
      int res = sm[p1] + sm[p2];
      for (auto [i, j] : ps[p2]) if (used[i][j]) {
        res -= a[i][j];
        break;
      }
      chmax(ans, res);
    }
    for (auto [i, j] : ps[p1]) used[i][j] = false;
  }
  cout << ans << '\n';
}