#pragma GCC optimize("O2")
#include <algorithm>
#include <array>
#include <bit>
#include <bitset>
#include <cassert>
#include <cctype>
#include <cfenv>
#include <cfloat>
#include <chrono>
#include <cinttypes>
#include <climits>
#include <cmath>
#include <compare>
#include <complex>
#include <concepts>
#include <cstdarg>
#include <cstddef>
#include <cstdint>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <deque>
#include <fstream>
#include <functional>
#include <initializer_list>
#include <iomanip>
#include <ios>
#include <iostream>
#include <istream>
#include <iterator>
#include <limits>
#include <list>
#include <map>
#include <memory>
#include <new>
#include <numbers>
#include <numeric>
#include <ostream>
#include <queue>
#include <random>
#include <ranges>
#include <set>
#include <span>
#include <sstream>
#include <stack>
#include <streambuf>
#include <string>
#include <tuple>
#include <type_traits>
#include <variant>

//#define int ll
#define INT128_MAX (__int128)(((unsigned __int128) 1 << ((sizeof(__int128) * __CHAR_BIT__) - 1)) - 1)
#define INT128_MIN (-INT128_MAX - 1)

#ifdef DEBUG
#define dbg(x) cout << (#x) << " = " << x << '\n'
#else
#define dbg(x)
#endif

namespace R = std::ranges;
namespace V = std::views;

using namespace std;

using ll = long long;
using ull = unsigned long long;
using ldb = long double;
//#define double ldb

template<class T, size_t N>
ostream& operator<<(ostream& os, const array<T, N> &arr) {
  for(const T &X : arr)
    os << X << ' ';
  return os;
}
template<class T>
ostream& operator<<(ostream& os, const vector<T> &vec) {
  for(const T &X : vec)
    os << X << ' ';
  return os;
}
template<class T>
ostream& operator<<(ostream& os, const set<T> &s) {
  for(const T &x : s)
    os << x << ' ';
  return os;
}

signed main() {
  ios::sync_with_stdio(false), cin.tie(NULL);

  int h, w; cin >> h >> w;
  vector a(h, vector<int>(w));
  for(auto &v : a)
    for(int &x : v)
      cin >> x;

  vector cand(4, vector<vector<array<int, 2>>>(h + w - 1));
  for(int i = 0; i < h; i++) {
    for(int j = 0; j < w; j++) {
      cand[0][i].push_back({i, j});
      cand[1][j].push_back({i, j});
      cand[2][i + j].push_back({i, j});
      cand[3][i - j + (w - 1)].push_back({i, j});
    }
  }

  int ans = 0;
  set<array<int, 2>> vis;
  auto dfs = [&](int i, auto self) -> void {
    if (i == 2) {
      int cost = 0;
      for(auto [x, y] : vis)
        cost += a[x][y];
      ans = max(ans, cost);
    } else {
      for(int j = 0; j < 4; j++) {
        for(int k = 0; k < h + w - 1; k++) {
          vector<array<int, 2>> del;
          for(auto x : cand[j][k]) {
            if (!vis.contains(x)) {
              del.push_back(x);
              vis.insert(x);
            }
          }
          self(i + 1, self);
          for(auto x : del)
            vis.erase(x);
        }
      }
    }
  };

  dfs(0, dfs);

  cout << ans << '\n';

  return 0;
}