#pragma GCC optimize("Ofast")
#pragma GCC target("avx2")

#define rd_init() char*rp=({char*mmap();mmap(0l,1l<<25,1,2,0,0ll);})
#define rd() ({int _v=0,_c;while(_c=*rp++-48,_c>=0)_v=_v*10+_c;_v;})
#define wt(v) ({unsigned _z=v;do*--wp=_z%10+48;while(_z/=10);})
#define wt1(v) ({char wbuf[64],*wp=wbuf+sizeof wbuf;wt(v);write(1,wp,wbuf+sizeof wbuf-wp);})
#define rep(v,e) for(typeof(e) v=0;v<e;++v)
#define max(a,b) (a>=b?a:b)
#define chmax(v,a) (v=v>=a?v:a)

int a[100];
int b[100];
int c[200];
int d[200];
int e[100][100];

int main(){
	rd_init();
	int h=rd();
	int w=rd();
	int z;
	{
		int a1=0,a2=0;
		rep(y,h){
			rep(x,w){
				int v=rd();
				a[y]+=v;
				b[x]+=v;
				c[y+x]+=v;
				d[y+w-1-x]+=v;
				e[y][x]=v;
			}
			if(a1<a[y]){
				a2=a1;
				a1=a[y];
			}else if(a2<a[y]){
				a2=a[y];
			}
		}
		z=a1+a2;
	}
	{
		int b1=0,b2=0;
		rep(x,w){
			if(b1<b[x]){
				b2=b1;
				b1=b[x];
			}else if(b2<b[x]){
				b2=b[x];
			}
		}
		chmax(z,b1+b2);
	}
	{
		int c1=0,c2=0;
		int d1=0,d2=0;
		rep(i,h+w-1){
			if(c1<c[i]){
				c2=c1;
				c1=c[i];
			}else if(c2<c[i]){
				c2=c[i];
			}
			if(d1<d[i]){
				d2=d1;
				d1=d[i];
			}else if(d2<d[i]){
				d2=d[i];
			}
		}
		chmax(z,c1+c2);
		chmax(z,d1+d2);
	}
	rep(y,h){
		rep(x,w){
			chmax(z,a[y]+b[x]-e[y][x]);
		}
		rep(i,h+w-1){
			{
				int t=a[y]+c[i];
				if(t>z){
					int x=i-y;
					if(x>=0&&x<w){
						t-=e[y][x];
					}
					chmax(z,t);
				}
			}
			{
				int t=a[y]+d[i];
				if(t>z){
					int x=y+w-1-i;
					if(x>=0&&x<w){
						t-=e[y][x];
					}
					chmax(z,t);
				}
			}
		}
	}
	rep(i,h+w-1){
		rep(x,w){
			{
				int t=b[x]+c[i];
				if(t>z){
					int y=i-x;
					if(y>=0&&y<h){
						t-=e[y][x];
					}
					chmax(z,t);
				}
			}
			{
				int t=b[x]+d[i];
				if(t>z){
					int y=i+1-w+x;
					if(y>=0&&y<h){
						t-=e[y][x];
					}
					chmax(z,t);
				}
			}
		}
		rep(j,h+w-1){
			int t=c[i]+d[j];
			if(t>z){
				if(!(i+j+1-w&1)){
					int y=i+j+1-w>>1;
					int x=i-j-1+w>>1;
					if(y>=0&&y<h&&x>=0&&x<w){
						t-=e[y][x];
					}
				}
				chmax(z,t);
			}
		}
	}
	wt1(z);
	_exit(0);
}