var a:array[1..20]of integer;
    m,n,k:byte;
    f:text;
    t:array[1..20,1..20]of integer;
    s:longint;

function sum:longint;
var s:longint; i,j:byte;
begin
 s:=0;
 for i:=1 to n do
 for j:=1 to m do
   s:=s+t[i,j]*a[i]*a[n+j];
 sum:=s;
end;

procedure afis;
var s1:longint;
begin
   s1:=sum;
   if s1>s then s:=s1;
end;

procedure bin(p:byte);
begin
  if p>k then afis
  else begin
  a[p]:=-1; bin(p+1);
  a[p]:=1; bin(p+1);
  end;
end;

procedure init;
var i,j:byte; f:text;
begin
  assign(f,'flip.in');
  reset(f);
  readln(f, n,m);
  for i:=1 to n do
  begin
    for j:=1 to m do
      read(f,t[i,j]);
    readln(f);
  end;
  close(f);
end;

procedure r(s:longint);
var f:text;
begin
  assign(f,'flip.out');
  rewrite(f);
  writeln(f,s);
  close(f);
end;

begin
  init;
  k:=n+m; s:=0;
  bin(1);
  r(s);
end.