program flip;
type Andi=array[1..100,1..100]of longint;
var f : text;
    A : Andi;
    m,n,i,j : longint;
    S1,S2,Sf : longint;
begin
     for i:=1 to n do
         for j:=1 to m do A[i,j]:=0;
     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 i:=1 to n do
         begin
              S1:=0; S2:=0;
              for j:=1 to m do
                  begin
                       S1:=S1+A[i,j];
                       S2:=S2-A[i,j];
                  end;
              if S1<S2 then
                 for j:=1 to m do A[i,j]:=-A[i,j];
         end;
     for j:=1 to m do
         begin
              S1:=0; S2:=0;
              for i:=1 to n do
                  begin
                       S1:=S1+A[i,j];
                       S2:=S2+(-A[i,j]);
                  end;
              if S1<S2 then
                 for i:=1 to n do A[i,j]:=-A[i,j];
         end;
     Sf:=0;
     for i:=1 to n do
         for j:=1 to m do
             Sf:=Sf+A[i,j];
     assign(f,'flip.out'); rewrite(f);
     write(f,Sf); reset(f);
     close(f);
end.