#include <bits/stdc++.h>
#include <atcoder/all>
using namespace std;
using ll = long long;
#define rep(i,n) for(int i=0;i<(int)(n);i++)
using mint = atcoder::modint1000000007;

int main(){
	int h,w;
	cin>>h>>w;
	vector<vector<ll>> a(h,vector<ll>(w));
	rep(i,h) rep(j,w) cin>>a.at(i).at(j);
	vector<int> dx={-1,-1,0,1,1,1};
	vector<int> dy={0,1,1,1,0,-1};
	auto isok=[&](int x,int y){
		return 0<=x&&x<h&&0<=y&&y<w;
	};
	auto select=[&](int x,int y,int i){
		ll res=0;
		while(isok(x,y)){
			res+=a.at(x).at(y);
			x+=dx.at(i);
			y+=dy.at(i);
		}
		return res;
	};
	auto del=[&](int x,int y,int i){
		while(isok(x,y)){
			a.at(x).at(y)=0;
			x+=dx.at(i);
			y+=dy.at(i);
		}
	};
	ll sm=0;
	rep(lp,2){
		ll ans=0;
		int x=0,y=0,i=0;
		rep(ch1,h+w-1){
			int x1=0,y1=0;
			if(ch1>=h) y1=ch1-h+1;
			else x1=ch1;
			rep(i1,6){
				ll tmp=select(x1,y1,i1);
				if(ans<tmp){
					ans=tmp;
					x=x1;
					y=y1;
					i=i1;
				}
			}
		}
		del(x,y,i);
		sm+=ans;
	}
	cout<<sm<<endl;
}