program p1;
var f,g:text;
    a:array[1..16,1..16] of longint;
    x,y:array[0..16] of longint;
    i,n,m,j,max,s:longint;
begin
     assign(f,'flip.in');reset(f);
     assign(g,'flip.out');rewrite(g);
     read(f,n,m);
     for i:=1 to n do
         for j:=1 to m do
             read(f,a[i,j]);
     max:=-2000000000;

     while x[0]=0 do
           begin
                i:=n;
                while x[i]=1 do begin x[i]:=0;i:=i-1; end;
                x[i]:=1;
                s:=0;
                for i:=1 to n do
                    for j:=1 to n do
                        if x[j]>0 then y[j]:=y[j]-a[i,j]
                                  else y[j]:=y[j]+a[i,j];
                for j:=1 to m do
                    if y[j]>0 then s:=s+y[j]
                              else for i:=1 to n do s:=s+a[i,j]*(-1);
                if max<s then max:=s;
                for i:=1 to m do
                    y[i]:=0;
           end;
     writeln(g,max);
close(f);
close(g);
end.