var a:array[1..20,1..20]of integer;
    m,n,i,j,k,c,v:integer;
    f,g:text;
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]);v:=-maxint;

for i:=1 to n do begin
k:=0;
for j:=1 to m do
if a[i,j]<0 then k:=k+1;
if v<k then begin v:=k;c:=i;end;end;

for j:=1 to m do
a[c,j]:=a[c,j]*(-1);v:=-maxint;

for j:=1 to m do begin
k:=0;
for i:=1 to n do
if a[j,i]<0 then k:=k+1;
if v<k then begin c:=j;v:=k;end;end;

for i:=1 to n do
a[i,c]:=a[i,c]*(-1);v:=0;

for i:=1 to n do
for j:=1 to m do
v:=v+a[i,j];
write(g,v);close(f);close(g);end.