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

//* ATCODER
#include<atcoder/all>
using namespace atcoder;
typedef modint998244353 mint;
//*/

/* BOOST MULTIPRECISION
#include<boost/multiprecision/cpp_int.hpp>
using namespace boost::multiprecision;
//*/

typedef long long ll;

#define rep(i, s, n) for (int i = (int)(s); i < (int)(n); i++)
#define rrep(i, s, n) for (int i = (int)(n)-1; i >= (int)(s); i--)

template <typename T> bool chmin(T &a, const T &b) {
	if (a <= b) return false;
	a = b;
	return true;
}

template <typename T> bool chmax(T &a, const T &b) {
	if (a >= b) return false;
	a = b;
	return true;
}

template <typename T> T max(vector<T> &a){
	assert(!a.empty());
	T ret = a[0];
	for (int i=0; i<(int)a.size(); i++) chmax(ret, a[i]);
	return ret;
}

template <typename T> T min(vector<T> &a){
	assert(!a.empty());
	T ret = a[0];
	for (int i=0; i<(int)a.size(); i++) chmin(ret, a[i]);
	return ret;
}

template <typename T> T sum(vector<T> &a){
	T ret = 0;
	for (int i=0; i<(int)a.size(); i++) ret += a[i];
	return ret;
}

int main(){
	int h, w; cin >> h >> w;
	
	vector a(h, vector<int>(w));
	
	rep(i,0,h){
		rep(j,0,w){
			cin >> a[i][j];
		}
	}

	vector<int> tat(w);
	vector<int> yok(h);
	vector<int> na1(h+w-1);
	vector<int> na2(h+w-1);

	rep(i,0,w){
		rep(j,0,h){
			tat[i] += a[j][i];
		}
	}
	
	rep(i,0,h){
		rep(j,0,w){
			yok[i] += a[i][j];
		}
	}

	rep(i,0,h+w-1){
		rep(j,0,w){
			if (i-j >= 0 && i-j < h && j >= 0 && j < w){
				na1[i] += a[i-j][j];
			}
		}
	}

	rep(i,0,h+w-1){
		rep(j,0,w){
			if (h-1-i+j >= 0 && h-1-i+j < h && j >= 0 && j < w){
				na2[i] += a[h-1-i+j][j];
			}
		}
	}

	int ans = 0;

	rep(x,0,h){
		rep(y,x+1,h){
			chmax(ans, yok[x] + yok[y]);
		}
	}
	
	rep(x,0,w){
		rep(y,x+1,w){
			chmax(ans, tat[x] + tat[y]);
		}
	}

	rep(x,0,h+w-1){
		rep(y,x+1,h+w-1){
			chmax(ans, na1[x] + na1[y]);
		}
	}
	
	rep(x,0,h+w-1){
		rep(y,x+1,h+w-1){
			chmax(ans, na2[x] + na2[y]);
		}
	}

	rep(x,0,h){
		rep(y,0,w){
			chmax(ans, yok[x] + tat[y] - a[x][y]);
		}
	}

	rep(x,0,h){
		rep(y,0,h+w-1){
			int del = 0;
			// (y-j, j)
			// (x, y-x)
			if (0 <= y-x && y-x < w) del = a[x][y-x];
			chmax(ans, yok[x] + na1[y] - del);
		}
		rep(y,0,h+w-1){
			int del = 0;
			// (h-1-y+j, j)
			// (x, x+y+1-h)
			// h-1-y+j = x
			// j = x+y+1-h
			if (0 <= x+y+1-h && x+y+1-h < w) del = a[x][x+y+1-h];
			chmax(ans, yok[x] + na2[y] - del);
		}
	}

	
	rep(x,0,w){
		rep(y,0,h+w-1){
			int del = 0;
			// (y-j, j)
			// (y-x, x)
			if (0 <= y-x && y-x < h) del = a[y-x][x];
			chmax(ans, tat[x] + na1[y] - del);
		}
		rep(y,0,h+w-1){
			int del = 0;
			// (h-1-y+j, j)
			// (h-1-y+x, x)
			if (0 <= h-1-y+x && h-1-y+x < h) del = a[h-1-y+x][x];
			chmax(ans, tat[x] + na2[y] - del);
		}
	}

	rep(x,0,h+w-1){
		rep(y,0,h+w-1){
			int del = 0;
			// (x-j, j)
			// (h-1-y+k, k)
			// x-k = h-1-y+k
			// 2k = x+y+1-h
			int k = (x+y+1-h)/2;
			if ((x+y+1-h)%2 == 0 && 0 <= x-k && x-k < h && 0 <= k && k < w){
				del = a[x-k][k];
			}
			chmax(ans, na1[x] + na2[y] - del);
		}
	}

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