program flip;
var f,g:text;
    a:array[1..16,1..16]of longint;
    b:array[0..16]of byte;
    s1,s2,max:longint;
    x,i,j,n,m,aux:integer;
begin
assign(f,'flip.in');reset(f);
assign(g,'flip.out');rewrite(g);
readln (f,n,m);
for i:=1 to n do
    begin
    for j:=1 to m do read (f,a[i,j]);
    readln(f);
    end;
x:=1;
max:=0;
while x>0 do
      begin
      if b[x]<2 then b[x]:=b[x]+1;
      if x=n then begin
                  s2:=0;
                  while j<=m do begin
                  		s1:=0;
                  		while i<n+1 do
				    begin
                                    if b[i]=2 then s1:=s1-a[i,j]
				    else s1:=s1+a[i,j];
                                    i:=i+1;
               			    end;
     				if s1<aux then s2:=s2-s1
			        else s2:=s2+s1;
    			        j:=j+1;
                                end;
    		  if s2>max then max:=s2;
    		  while b[x]=2 do
                        begin
			x:=x-1;
			end;
   		  end
      else begin
	   x:=x+1;
	   b[x]:=0;
	   end;
      end;
writeln(g,max);
close(f);
close(g);   
end.