program p1;
var n,m:byte;
    f,g:text;
    i,nr,nr1,j,k,s,u1,u,i1,i2,k1,max:longint;
    a,b:array[0..20,0..20] of longint;
    d,c:array[0..132] of longint;
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 begin read(f,a[i,j]); b[i,j]:=a[i,j]; max:=max+b[i,j]; end;
                  readln(F);
                  end;
 for i:=1 to (1 shl n )-1 do begin
                k:=0;  u:=0;
                while i>1 shl k do inc(K);
                for j:=0 to k do
                        if i and (1 shl j) <>0 then  begin
                                        inc(U);
                                        c[u]:=j+1;
                                                end;
                for j:=1 to u do
                        for i1:=1 to m do
                                    b[c[j],i1]:=b[c[j],i1]*-1;
                for i1:=1 to ( 1 shl m )-1 do begin
                        k1:=0;u1:=0;
                        while i1>1 shl k1 do inc(k1);
                        for j:=0 to k1 do
                                if i1 and (1 shl j)<>0 then begin
                                                inc(u1);
                                                d[u1]:=j+1;
                                                        end;
                        for j:=1 to u1 do
                                for i2:=1 to n do
                                        b[i2,d[j]]:=b[i2,d[j]]*-1;
                s:=0;
                for i2:=1 to n do
                        for j:=1 to m do begin
                                        s:=s+b[i2,j];
                                        if s>max then begin
                                                max:=s;
                                                 break;
                                                        end;
                                        b[i2,j]:=a[i2,j];
                                        end; end;
                           end;
writeln(g,max);
close(F);
close(G);
end.