#include <bits/stdc++.h>
using namespace std;


int main(){
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);

    int H,W; cin >> H >> W;
    vector<vector<int>> A(H,vector<int>(W));
    for(auto &h : A) for(auto &w : h) cin >> w; 
    if(H == 1 && W == 1){cout << A.at(0).at(0) << endl; return 0;}

    vector<pair<set<pair<int,int>>,int>> beam;
    for(int i=0; i<H; i++){
        for(int k=0; k<W; k++){
            if(!(i == 0 || i == H-1 || k == 0 || k == W-1)) continue;

            bool one = true;
            for(int a=-1; a<=1; a++) for(int b=-1; b<=1; b++){
                if(a == 0 && b == 0) continue;
                int x = i, y = k, p = 0;
                set<pair<int,int>> visit;
                while(true){
                    p += A.at(x).at(y);
                    visit.insert({x,y});

                    x += a; y += b;
                    if(x < 0 || x >= H || y < 0 || y >= W) break;
                }
                if(!one && visit.size() == 1) continue;
                if(one && visit.size() == 1) one = false;
                beam.push_back({visit,p});
            }
        }
    }

    int bs = beam.size(),answer = 0;
    for(int i=0; i<bs; i++){
        auto &[s1,p1] = beam.at(i); 
        for(int k=i+1; k<bs; k++){
            auto &[s2,p2] = beam.at(k);

            int now = p1+p2;
            for(auto [x,y] : s1){
                if(s2.count(make_pair(x,y))) now -= A.at(x).at(y);  
            }
            answer = max(answer,now);
        }
    }
    cout << answer << endl;
}