program flip;
var f:text;x:array[1..16,1..16] of longint;m,n,i,j:integer;
max,max1,e:int64;t:boolean;
begin
        assign(f,'flip.in');
        reset(f);
        readln(f,n,m);
        for i:=1 to n do begin
                for j:=1 to m do read(f,x[i,j]);
                readln(f);
                end;
        close(f);
        repeat
        t:=true;
        max1:=max;
        e:=0;
        for i:=1 to n do begin
                max:=0;
                for j:=1 to m do max:=max+x[i,j];
                if max<0 then begin
                        for j:=1 to m do x[i,j]:=x[i,j]*-1;
                        t:=false;
                        end;
                end;
        for j:=1 to m do begin
                max:=0;
                for i:=1 to n do max:=max+x[i,j];
                if max<0 then begin
                        for i:=1 to n do x[i,j]:=x[i,j]*-1;
                        t:=false;
                        max:=max*-1;
                        end;
                e:=e+max;
                end;
        until (max1=e) or (t=true);
        assign(f,'flip.out');
        rewrite(f);
        write(f,e);
        close(f);
end.