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-3;   
i:=i-1;   
j:=2;   
j:=j shl m-3;   
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.