program flip;
var n,m,i,j:0..16;
    c,d:-16000000..16000000;
    a:array[0..16,0..16]of -16000000..16000000;
    t:text;
begin
 assign(t,'flip.in'); reset(t);
        readln(t,n,m);
        for i:=1 to n do begin
                c:=0;
                d:=0;
                for j:=1 to m do begin
                        read(t,a[i,j]);
                        c:=c+a[i,j];
                        d:=d-a[i,j];
                end;
                if d>c then for j:=1 to m do a[i,j]:=-a[i,j];
                readln(t);
        end;
 close(t);


 for j:=1 to m do begin
        c:=0;
        d:=0;
        for i:=1 to n do begin
                c:=c+a[i,j];
                d:=d-a[i,j];
        end;
        if d>c then for i:=1 to n do a[i,j]:=-a[i,j];
 end;

 c:=0;
 for i:=1 to n do
        for j:=1 to m do c:=c+a[i,j];

 assign(t,'flip.out'); rewrite(t);
        writeln(t,c);
 close(t);
end.