type mat=array[0..16,0..16]of longint;

var a:mat;
    f,g:text;
    m,n,s:longint;
    i,j:byte;
procedure linie(x,y:byte; var a:mat);
var i :byte;
begin
for i := 1 to y do a[x,i]:=-a[x,i];
end;

procedure col(x,y:byte; var a:mat);
var i : byte;
begin
for i := 1 to y do a[i,x]:=-a[i,x];
end;

begin
assign(f,'flip.in'); reset(f); assign(g,'flip.out'); rewrite(g);
readln(f,m,n);
for i := 1 to m do begin
   s:=0;
   for j := 1 to n do  begin
        read(f,a[i,j]); s:=s+a[i,j];
                       end;
   a[i,0] := s;
   readln(f);
                   end;

for i := 1 to n do begin
    s:=0;
    for j := 1 to m do
         s:=s+a[j,i];
    a[0,i]:=s;
                   end;
j:=0;
for i := 1 to m do if a[i,j]<0 then linie(i,n,a);
i:=0;
for j := 1 to n do if a[i,j]<0 then col(j,m,a);

s:=0;
for i := 1 to m do for j := 1 to n do s := s+ a[i,j];
writeln(g,s);
close(f);
close(g);
end.