var a:array[1..16,1..16] of integer;
    q:array[1..32] of integer;
    i,j,n,m,l,c,s,max,t,k:integer;
    f,g:text;
begin
assign(f,'flip.in');reset(f);
assign(g,'flip.out');rewrite(g);
readln(f,n,m);
for i:=1 to n do
  begin
    for j:=1 to m do
      read(f,a[i,j]);
    readln(f);
  end;
t:=m+n;s:=0;max:=0;
for i:=1 to (1 shl t)-1 do
  begin
    for j:=0 to t do
      if (1 shl j) and i >0 then q[j+1]:=1 else q[j+1]:=-1;
    for l:=1 to n do
      for c:=1 to m do
        s:=s+a[l,c]*q[l]*q[c+n];
    if s>max then max:=s;
    s:=0
  end;
writeln(g,max);
close(f);close(g);
end.