program infoarena_flip;
var i,j,k,k1,k2,m,n,x,y,s,smax,i2,j2,k3:longint;
    a:array[1..16,1..16] of longint;
    b1,b2:array[1..16] of byte;

begin
assign(input,'flip.in');
reset(input);
read(n);readln(m);
for i:=1 to n do
 for j:=1 to m do
  read(a[i,j]);
close(input);
smax:=0;

for i:=1 to n do
 for j:=1 to m do
  begin
   smax:=smax+a[i,j];
  end;


i:=2;
i:=i shl n-2;
i:=i-1;
j:=2;
j:=j shl m-2;
j:=j-1;

for k1:=1 to i do
 for k2:=1 to j do
  begin
   k:=k1;
   x:=1;
   while (k<>0){and(k<>1)} do
    begin
     b1[x]:=k mod 2;
     k:=k div 2;
     x:=x+1;
     end;
    b1[x]:=k;
    k:=0;

   k:=k2;
   y:=1;
   while (k<>0){and(k<>1)} do
    begin
     b2[y]:=k mod 2;
     k:=k div 2;
     y:=y+1;
     end;
   b2[x]:=k;
   k:=0;

s:=0;
for i2:=1 to n do
 for j2:=1 to m do
  begin
   if b1[i2]=1 then k3:=-1
               else k3:=1;
   if b2[j2]=1 then k3:=k3*(-1);
   s:=s+a[i2,j2]*k3;
  end;
if s>smax then smax:=s;

  end;

assign(output,'flip.out');
rewrite(output);
writeln(smax);
close(output);

end.