var a,sum:array[0..110,0..110] of longint;

s:array[0..110] of longint;

n,i,j,k:longint;

ans,max,now,maxnow:longint;

function maxx(a,b:longint):longint;

begin

if a>b then exit(a); exit(b);

end;

begin

readln(n);

for i:=1 to n do

for j:=1 to n do read(a[i,j]);

for i:=1 to n do

for j:=1 to n do

sum[i,j]:=sum[i-1,j]+a[i,j];

max:=-oo;

for i:=1 to n do

for j:=i to n do

begin

fillchar(s,sizeof(s),0);

for k:=1 to n do

begin

now:=sum[j,k]-sum[i-1,k];

s[k]:=maxx(s[k-1]+now,now);

end;

maxnow:=-oo;

for k:=1 to n do

if s[k]>maxnow then maxnow:=s[k];

if maxnow>max then max:=maxnow;

end;

writeln(max);

end.