var a:array[1..17,1..17] of longint;
    v:array[1..17] of -1..1;
    f,g:text;  n,m,i,j,k,s1,s2,s,max:longint;
begin
assign(f,'flip.in'); reset(f);
assign(g,'flip.out'); rewrite(g);
read(f,n,m);  max:=-1;
for i:=1 to n do
for j:=1 to m do read(f,a[i,j]) ;
k:=1; for i:=1 to 16 do v[i]:=1;
while k<=n do begin
s:=0;
for i:=1 to n do
if v[i]=1 then begin v[i]:=-1; break;  end
          else begin v[i]:=1; if i=k then inc(k);  end;
for j:=1 to m do begin
s1:=0; s2:=0;
for i:=1 to n do if v[i]*a[i,j]>=0 then s1:=s1+v[i]*a[i,j]
                              else s2:=s2-v[i]*a[i,j];
if s1<s2 then for i:=1 to n do s:=s+a[i,j]*v[i]*(-1)
         else for i:=1 to n do s:=s+a[i,j]*v[i];
end;
if s>max then max:=s;
end;
write(g,max);
close(g);
end.