var a,b:array[0..20,0..16] of longint;
    f:text;
    i,s,smax,j,m,n:integer;
    ok:boolean;
begin
assign(f,'flip.in');
reset(f);
read(f,n,m);
for i:=1 to n do begin
    s:=0;
    for j:=1 to m do begin
        read(f,a[i,j]);
        smax:=smax+a[i,j];
        s:=s+a[i,j];
        end;
    a[i,0]:=s;
    end;
close(f);
for i:=1 to m do
    for j:=1 to n do
        a[0,i]:=a[0,i]+a[j,i];
ok:=true;
while ok=true do begin
      ok:=false;
for i:=1 to n do
    if a[i,0]<0 then begin
       ok:=true;
       for j:=1 to m do begin
           a[i,j]:=a[i,j]*(-1);
           a[i,0]:=a[i,0]+2*a[i,j];
           smax:=smax+2*a[i,j];
           a[0,j]:=a[0,j]+2*a[i,j];
           end;
       end;
for i:=1 to m do
    if a[0,i]<0 then begin
       ok:=true;
       for j:=1 to n do begin
           a[j,i]:=a[j,i]*(-1);
           a[j,0]:=a[j,0]+2*a[j,i];
           smax:=smax+2*a[j,i];
           a[0,i]:=a[0,i]+2*a[j,i];
           end;
       end;
end;
assign(f,'flip.out');
rewrite(f);
write(f,smax);
close(f);
end.