type matrice=array[1..16,1..16] of integer;
        vector=array[1..16] of longint;
var a:matrice;
   v1,v2:vector;
   s:longint;
   m,n,i,j:integer;
   f,g:text;
Begin
Assign(f,'flip.in');Reset(f);
Assign(g,'flip.out');Rewrite(g);
Read(f,n,m);
For i:=1 to n do begin
For j:=1 to m do
Read(f,a[i,j]);end;
s:=0;
For i:=1 to n do begin
v1[i]:=0;
v2[i]:=0;
end;
For i:=1 to n do begin
For j:=1 to m do begin
v1[i]:=v1[i]+a[i,j];
v2[i]:=v2[i]-a[i,j];
end;
If (v2[i]>=v1[i]) then a[i,j]:=(-1)*a[i,j];
end;
For j:=1 to m do begin
v1[j]:=0;
v2[j]:=0;
end;
For j:=1 to m do begin
For i:=1 to n do begin
v1[j]:=v1[j]+a[i,j];
v2[j]:=v2[j]-a[i,j];end;
If (v2[j]>=v1[j]) then a[i,j]:=(-1)*a[i,j];end;
For i:=1 to n do
For j:=1 to m do
s:=s+a[i,j];
Write(g,s);
close(f);close(g);end.