#include<bits/stdc++.h>
#include<atcoder/all>
#define rep(i,n) for(int i=0;i<n;i++)
using namespace std;
using namespace atcoder;
typedef long long ll;
typedef vector<int> vi;
typedef vector<long long> vl;
typedef vector<vector<int>> vvi;
typedef vector<vector<long long>> vvl;
typedef long double ld;

template <int m>
std::ostream& operator<<(std::ostream& os, const atcoder::static_modint<m>& a) {os << a.val(); return os;}
template<typename T>
istream& operator>>(istream& is, vector<T>& v){int n = v.size(); assert(n > 0); rep(i, n) is >> v[i]; return is;}
template<typename T>
ostream& operator<<(ostream& os, const vector<T>& v){int n = v.size(); rep(i, n) os << v[i] << (i == n - 1 ? "\n" : " "); return os;}
template <typename T>
ostream& operator<<(ostream& os, const vector<vector<T>>& v){int n = v.size(); rep(i, n) os << v[i] << (i == n - 1 ? "\n" : ""); return os;}

int main(){
	int h, w;
	cin >> h >> w;
	vector<vector<int>> a(h, vi(w));
	rep(y, h) cin >> a[y];
	int ans = 0;
	int n = h + w + (h + w - 1) + (h + w - 1);
	vi v(2);
	for(v[0] = 0; v[0] < n; v[0]++){
		for(v[1] = 0; v[1] < n; v[1]++){
			unordered_set<int> se;
			rep(i, 2){
				if(v[i] < h){
					int y = v[i];
					rep(x, w) se.insert(y * w + x);
				}else if(v[i] < h + w){
					int x = v[i] - h;
					rep(y, h) se.insert(y * w + x);
				}else if(v[i] < h + w + (h + w - 1)){
					int s = v[i] - (h + w);
					rep(y, h){
						int x = s - y;
						if(x >= 0 and x < w) se.insert(y * w + x);
					}
				}else{
					int d = v[i] - (h + w + (h + w - 1)) - (w - 1);
					rep(y, h){
						int x = y - d;
						if(x >= 0 and x < w) se.insert(y * w + x);
					}
					
				}
			}
			int tmp = 0;
			for(auto z : se){
				int y = z / w;
				int x = z % w;
				tmp += a[y][x];
			}
			ans = max(ans, tmp);
		}
	}
	cout << ans;
	return 0;
}