#pragma GCC target("avx2")
#pragma GCC optimize("O3")
#pragma GCC optimize("unroll-loops")

#include <bits/stdc++.h>

#include <atcoder/all>
using namespace std;
using namespace atcoder;
typedef long long ll;
#define rep(i, n) for (int i = 0; i < (int)(n); i++)
#define repr(i, n) for (int i = (int)(n)-1; i >= 0; i--)
#define repk(i, k, n) for (int i = k; i < (int)(n); i++)
#define all(v) v.begin(), v.end()
#define mod1 1000000007
#define mod2 998244353
#define mod3 100000007
#define vi vector<int>
#define vs vector<string>
#define vc vector<char>
#define vl vector<ll>
#define vb vector<bool>
#define vvi vector<vector<int>>
#define vvc vector<vector<char>>
#define vvl vector<vector<ll>>
#define vvb vector<vector<bool>>
#define vvvi vector<vector<vector<int>>>
#define vvvl vector<vector<vector<ll>>>
#define pii pair<int, int>
#define pil pair<int, ll>
#define pli pair<ll, int>
#define pll pair<ll, ll>
#define vpii vector<pair<int, int>>
#define vpll vector<pair<ll, ll>>
#define vvpii vector<vector<pair<int, int>>>
#define vvpll vector<vector<pair<ll, ll>>>

template <typename T>
void debug(T e) {
    cerr << e << endl;
}

template <typename T>
void debug(vector<T> &v) {
    rep(i, v.size()) { cerr << v[i] << " "; }
    cerr << endl;
}

template <typename T>
void debug(vector<vector<T>> &v) {
    rep(i, v.size()) {
        rep(j, v[i].size()) { cerr << v[i][j] << " "; }
        cerr << endl;
    }
}

template <typename T>
void debug(vector<pair<T, T>> &v) {
    rep(i, v.size()) { cerr << v[i].first << " " << v[i].second << endl; }
}

template <typename T>
void debug(set<T> &st) {
    for (auto itr = st.begin(); itr != st.end(); itr++) {
        cerr << *itr << " ";
    }
    cerr << endl;
}

template <typename T>
void debug(multiset<T> &ms) {
    for (auto itr = ms.begin(); itr != ms.end(); itr++) {
        cerr << *itr << " ";
    }
    cerr << endl;
}

template <typename T>
void debug(map<T, T> &mp) {
    for (auto itr = mp.begin(); itr != mp.end(); itr++) {
        cerr << itr->first << " " << itr->second << endl;
    }
}

void debug_out() { cerr << endl; }

template <typename Head, typename... Tail>
void debug_out(Head H, Tail... T) {
    cerr << H << " ";
    debug_out(T...);
}

int main() {
    ll H, W;
    cin >> H >> W;
    vector<vector<ll>> A(H, vector<ll>(W));
    for (ll i = 0; i < H; i++) {
        for (ll j = 0; j < W; j++) {
            cin >> A[i][j];
        }
    }
    vector<ll> dx = {1, 1, 0, -1};
    vector<ll> dy = {0, 1, 1, 1};
    vector<pll> p(0);
    for (ll i = 0; i < H; i++) {
        for (ll j = 0; j < W; j++) {
            if (i >= 1 && i < H - 1 && j >= 1 && j < W) {
                continue;
            }
            p.push_back(pll(i, j));
        }
    }
    ll ans = 0;
    vector<vector<bool>> seen(H, vector<bool>(W, false));
    for (ll i = 0; i < p.size(); i++) {
        for (ll j = i; j < p.size(); j++) {
            for (ll k = 0; k < 4; k++) {
                for (ll l = 0; l < 4; l++) {
                    ll now_x = p[i].first;
                    ll now_y = p[i].second;
                    vector<pll> fst;
                    while (true) {
                        fst.push_back(pll(now_x, now_y));
                        seen[now_x][now_y] = true;
                        now_x += dx[k];
                        now_y += dy[k];
                        if (now_x < 0 || now_x >= H || now_y < 0 ||
                            now_y >= W) {
                            break;
                        }
                    }
                    now_x = p[j].first;
                    now_y = p[j].second;
                    while (true) {
                        fst.push_back(pll(now_x, now_y));
                        seen[now_x][now_y] = true;
                        now_x += dx[l];
                        now_y += dy[l];
                        if (now_x < 0 || now_x >= H || now_y < 0 ||
                            now_y >= W) {
                            break;
                        }
                    }
                    sort(all(fst));
                    ll anssub = 0;
                    for (ll m = 0; m < fst.size(); m++) {
                        if (m == 0) {
                            anssub += A[fst[m].first][fst[m].second];
                        } else if (!(fst[m].first == fst[m - 1].first &&
                                     fst[m].second == fst[m - 1].second)) {
                            anssub += A[fst[m].first][fst[m].second];
                        }
                    }
                    ans = max(ans, anssub);
                }
            }
        }
    }
    cout << ans << endl;
}