#include <bits/stdc++.h>
// #include <x86intrin.h>
using namespace std;
using namespace numbers;



int main(){
	cin.tie(0)->sync_with_stdio(0);
	cin.exceptions(ios::badbit | ios::failbit);
	int nr, nc;
	cin >> nr >> nc;
	vector<vector<int>> a(nr, vector<int>(nc));
	for(auto &x: a | ranges::views::join){
		cin >> x;
	}
	static const vector<pair<int, int>> dr8{{1, 0}, {1, 1}, {0, 1}, {-1, 1}, {-1, 0}, {-1, -1}, {0, -1}, {1, -1}};
	int res = 0;
	for(auto [dx0, dy0]: dr8){
		for(auto x0 = 0; x0 < nr; ++ x0){
			for(auto y0 = 0; y0 < nc; ++ y0){
				if(x0 == 0 || x0 == nr - 1 || y0 == 0 || y0 == nc - 1){
					vector<vector<int>> vis(nr, vector<int>(nc));
					int temp = 0;
					for(auto x = x0, y = y0; 0 <= min(x, y) && x < nr && y < nc; x += dx0, y += dy0){
						vis[x][y] = true;
						temp += a[x][y];
					}
					for(auto [dx1, dy1]: dr8){
						for(auto x1 = 0; x1 < nr; ++ x1){
							for(auto y1 = 0; y1 < nc; ++ y1){
								if(x1 == 0 || x1 == nr - 1 || y1 == 0 || y1 == nc - 1){
									int cur = temp;
									for(auto x = x1, y = y1; 0 <= min(x, y) && x < nr && y < nc; x += dx1, y += dy1){
										if(!vis[x][y]){
											cur += a[x][y];
										}
									}
									if(res < cur){
										res = cur;
									}
								}
							}
						}
					}
				}
			}
		}
	}
	cout << res << "\n";
	return 0;
}

/*

*/

////////////////////////////////////////////////////////////////////////////////////////
//                                                                                    //
//                                   Coded by Aeren                                   //
//                                                                                    //
////////////////////////////////////////////////////////////////////////////////////////