task2.pas

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

procedure readNext(var s: string; var i: integer; var n: integer);
const
  ord0: integer = 48;
begin
  var c: char := s[i];
  var minus: integer := 1;
  var ls: integer := length(s);
  
  if c = '-' then
  begin
    minus := -1;
    i := i + 1;
  end;
  
  n := 0;
  while i <= ls do
  begin
    c := s[i];
    if c = ' ' then
      break;
    n := n * 10 + (ord(c) - ord0);
    i := i + 1;
  end;
  
  i := i + 1;
  n := n * minus;
end;

begin
  var str: string;
  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
    ReadLn(str);
    var nextInd: integer = 1;
    for var j := 0 to n do
    begin
      ReadNext(str, nextInd, x);
      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;
  end;
  
  Write(r);
end.