program flip;
var f,g:text;
    a:array[1..16,1..16]of longint; 
    b:array[0..100]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;
aux:=0;
while x>0 do 
      begin 
      if aux=1 then aux:=0;
      if b[x]<2 then b[x]:=b[x]+1;
      if x=n then begin 
                  s2:=0;  
                  while j<=n 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;
      aux:=aux+1;
      end;
writeln(g,max);
close(f);
close(g);   
end.