#include<bits/stdc++.h>
using namespace std;
using ll = long long;
using pll = pair<ll, ll>;
#define drep(i, cc, n) for (ll i = (cc); i <= (n); ++i)
#define rep(i, n) drep(i, 0, n - 1)
#define all(a) (a).begin(), (a).end()
#define pb push_back
#define fi first
#define se second
mt19937_64 rng(chrono::system_clock::now().time_since_epoch().count());
const ll MOD1000000007 = 1000000007;
const ll MOD998244353 = 998244353;
const ll MOD[3] = {999727999, 1070777777, 1000000007};
const ll LINF = 1LL << 60LL;
const int IINF = (1 << 30) - 1;


void solve(){
    int h, w; cin >> h >> w;
    vector<vector<int>> a(h+2, vector<int>(w+2, 0));
    for(int i=1; i<=h; i++) for(int j=1; j<=w; j++) cin >> a[i][j];

    int ans = 0;
    int di[8] = {-1, -1, -1, 0, 0, 1, 1, 1};
    int dj[8] = {-1, 0, 1, -1, 1, -1, 0, 1};
    vector<pair<int, int>> E;
    for(int i=0; i<=h+1; i++) for(int j=0; j<=w+1; j++){
        if(!(i==0 || i==h+1 || j==0 || j==w+1)) continue;
        if(i==h+1){
            if(j!=0 && j!=w+1) continue;
        }
        E.pb({i, j});
    }
    vector<vector<bool>> visited(h+2, vector<bool>(w+2, false));
    for(auto [i0, j0] : E){
        for(auto [i1, j1] : E){
            for(int k0=0; k0<8; k0++) for(int k1=0; k1<8; k1++){
                int sum = 0;
                {
                    int now_i = i0, now_j = j0;
                    while(true){
                        now_i = now_i + di[k0], now_j = now_j + dj[k0];
                        if(now_i<=0 || now_i>=h+1 || now_j<=0 || now_j>=w+1) break;
                        sum += a[now_i][now_j];
                        visited[now_i][now_j] = true;
                    }
                }
                {
                    int now_i = i1, now_j = j1;
                    while(true){
                        now_i = now_i + di[k1], now_j = now_j + dj[k1];
                        if(now_i<=0 || now_i>=h+1 || now_j<=0 || now_j>=w+1) break;
                        if(!visited[now_i][now_j]) sum += a[now_i][now_j];
                    }
                }
                {
                    int now_i = i0, now_j = j0;
                    while(true){
                        now_i = now_i + di[k0], now_j = now_j + dj[k0];
                        if(now_i<=0 || now_i>=h+1 || now_j<=0 || now_j>=w+1) break;
                        visited[now_i][now_j] = false;
                    }
                }
                ans = max(ans, sum);
            }
        }
    }

    cout << ans << '\n';
}

int main(){
    cin.tie(nullptr);
    ios::sync_with_stdio(false);
    
    int T=1;
    //cin >> T;
    while(T--) solve();
}