var f,g:text;m,n,i,j:integer;s,sk:longint;
    a:array[1..16,1..16]of longint;v:array[1..16]of longint;
begin
assign(f,'flip.in');reset(f);
assign(g,'flip.out');rewrite(g);
read(f,n,m);
for i:=1 to n do
for j:=1 to m do read(f,a[i,j]);
for i:=1 to n do begin
for j:=1 to m do begin
v[j]:=a[i,j];s:=s+a[i,j];end;
for j:=1 to m do sk:=sk+(v[i]*-1);
if sk>s then for j:=1 to m do a[i,j]:=a[i,j]*-1;end;
for j:=1 to m do begin
for i:=1 to n do begin
v[i]:=a[j,i];s:=s+a[j,i];end;
for i:=1 to n do sk:=sk+(v[i]*-1);
if sk>s then for i:=1 to n do a[j,i]:=a[j,i]*-1;end;
for i:=1 to n do
for j:=1 to m do s:=s+a[i,j];
write(g,s);close(f);close(g);end.