acmp360.pas

procedure maxi(var a: integer; b: integer);
begin
  if a < b then
    a := b
end;

begin
  var b, c: array [0..1999] of shortint;
  var r, n, x, bj, bp, ap, app, s1, s2: integer;
  
  ReadLn(n);  
  r := -310;
  n := n - 1;
  
  for var i := 0 to n do
  begin
    var s := System.Console.ReadLine;
    var nextInd := 1;
    for var j := 0 to n do
    begin
      x := s.ReadInteger(nextInd);
      
      bp := bj;
      bj := b[j];
      s1 := x + ap;
      s2 := x + bj;
      
      if i > 0 then
      begin
        if j > 0 then
        begin
          maxi(r, s1 + max(bj, bp));
          maxi(r, s2 + bp);
        end;
        if j < n then
          maxi(r, s2 + b[j + 1]);
        if i > 1 then
          maxi(r, s2 + c[j]);
      end;
      
      if j > 1 then
      begin
        maxi(r, s1 + app);
      end;
      
      app := ap;
      ap := x;
      c[j] := bj;
      b[j] := x;
    end;
    if i mod 9 = 0 then
      System.GC.Collect;
  end;
  
  Write(r);
end.