var a:array[1..16,1..16] of longint;
v:array[1..32] of 0..1;
m,n,i,j,s,smax:longint;
f,g:text;
k:boolean;
begin
assign(f,'flip.in');
assign(g,'flip.out');
reset(f);rewrite(g);
readln(f,m,n);
for i:=1 to m do
    begin
    for j:=1 to n do
        read(f,a[i,j]);
    readln(f);
    end;
smax:=-maxlongint;
repeat
      s:=0;
      for i:=1 to m do
          for j:=1 to n do
              if (v[i]=1) xor (v[m+j]=1) then
                 s:=s-a[i,j]
              else
                  s:=s+a[i,j];
      if s>smax then
         smax:=s;
      i:=m+n;
      while v[i]=1 do
            i:=i-1;
      v[i]:=1;
      for j:=i+1 to m+n do
          v[j]:=0;
      k:=true;
      for i:=1 to m+n do
          if v[i]=0 then
             begin
             k:=false;
             break;
             end;
until k=true;
write(g,smax);
close(f);close(g);
end.