program flip;
VAR
        v:array[1..16,1..16] of longint;
        i,j,n,m:integer;
        f,g:text;
        s,s1,s2:longint;
Begin
        assign(f,'flip.in'); Reset(f);
        assign(g,'flip.out'); Rewrite(g);
        readln(f,n,m);
        for i:=1 to n do begin
                for j:=1 to m do
                        read(f,v[i,j]);
                readln(f);
        end;
        for i:=1 to n do begin
                s1:=0;
                s2:=0;
                for j:=1 to m do begin
                        s1:=s1+v[i,j];
                        s2:=s2-v[i,j];
                end;
                if s2>s1 then for j:=1 to m do
                        v[i,j]:=v[i,j]*(-1);
        end;
        for j:=1 to m do begin
                s1:=0;
                s2:=0;
                for i:=1 to n do begin
                        s1:=s1+v[i,j];
                        s2:=s2-v[i,j];
                end;
                if s2>s1 then for i:=1 to n do
                        v[i,j]:=v[i,j]*(-1);
        end;
        s:=0;
        for i:=1 to n do
                for j:=1 to m do
                        s:=s+v[i,j];
        write(g,s);
        close(g);
end.