Maximal triple task

task.pas

var
  b, c: array [0..1999] of shortint;
  r, n, s, i, j, x, bj, bp, ap, app: integer;

function max(a, b: integer): integer;
begin
  if a > b then
    max := a
  else
    max := b;
end;

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

begin
  Read(n);  
  r := -310;
  n := n - 1;
  
  for i := 0 to n do
    for j := 0 to n do
    begin
      Read(x);
      bp := bj;
      bj := b[j];
      
      if i > 0 then
      begin
        if j > 0 then
        begin
          s := x + ap;
          maxi(r, s + max(bj, bp));
          maxi(r, x + bj + bp);
        end;
        if j < n then
          maxi(r, x + bj + b[j + 1]);
        if i > 1 then
          maxi(r, x + bj + c[j]);
      end;
      
      if j > 1 then
      begin
        maxi(r, x + ap + app);
      end;
      
      app := ap;
      ap := x;
      c[j] := bj;
      b[j] := x;
    end;
  
  Write(r);
end.