program flipah;

var n,m,s,s1,i,j:integer;
    a:array[integer,1..17] of integer;
    f:text;

begin
 assign(f,'flip.in');
 reset(f);
 readln(f,n,m);
 for i:=1 to n do for j:=1 to m do read(f,a[i,j]);
 close(f);
 for j:=1 to m do begin
                   s:=0;
                   s1:=0;
                   for i:=1 to n do begin
                                      s:=s+a[i,j];
                                      s1:=s1+(a[i,j]*(-1));
                                     end;
                   if s<s1 then for i:=1 to n do a[i,j]:=a[i,j]*(-1);
                   end;
 for i:=1 to n do begin
                   s:=0;
                   s1:=0;
                   for j:=1 to m do begin
                                       s:=s+a[i,j];
                                       s1:=s+(a[i,j]*(-1));
                                    end;
                  if s<s1 then for j:=1 to m do a[i,j]:=a[i,j]*(-1);
                  end;
 s:=0;
 for i:=1 to n do for j:=1 to m do s:=s+a[i,j];
 assign(f,'flip.out');
 rewrite(f);
 write(f,s);
 close(f);
 end.