{$n+}
Uses Graph, Crt;

Const
  nn = 50;

Var N, main_n: Integer;
Type
 TGraph = Array[1 .. nn, 1 .. nn] Of LongInt;

Procedure Warshall(Var a: TGraph; c: TGraph);
Var i, j, k: Integer;
Begin
  For i := 1 To n Do
    For j := 1 To n Do a[i,j] := c[i,j];

  For k := 1 To n Do
    For i := 1 To n Do
      For j := 1 To n Do

        If (a[i,k]+a[k,j] < a[i,j]) Then
          a[i,j] := a[i,k] + a[k,j]
End;

Procedure ReadFileGraph(Var a: TGraph);
Var
  i,j: integer;
  filename: String;
  f: Text;
Begin

  Write('Enter file name: '); ReadLn(filename);
  Write(' main N = '); ReadLn(main_N);
  Assign(f, filename); Reset(f);
  Readln(f,N);
  For i := 1 To n Do
    For j := 1 To n Do
      Read(f,a[i,j]);
  Close(f);
End;

Procedure ReadGraph(Var a: TGraph);
Var
  i, j: Integer;
Begin
  WriteLn('matriza smezhnosti');
  Write('n = '); ReadLn(n);
  Write(' main N = '); ReadLn(main_N);

  For i := 1 To n Do
    For j := 1 To n Do Begin
      Write('G', i, ',', j, '= ');
      ReadLn(a[i,j]);
    End;
  WriteLn;
End;


(* Volvo stuff *)
procedure Arrow(xs, ys, xf, yf: longint;
          color: byte);
const
  delta_phi = 1;
  delta_len = 10;
  R2D = 180 / Pi;
type
  polar = record
    phi, len: double;
  end;
  point = record
    x, y: longint;
  end;

  function sign(x: longint): longint;
  begin
    if x = 0 then sign := 1
    else sign := x div abs(x);
  end;

  procedure polar_to_decart(var plr: polar;
            var pnt: point);
  begin
    pnt.x := xs + sign(xf - xs) *
                  trunc(plr.len * cos(plr.phi/R2D));
    pnt.y := ys + sign(yf - ys) *
                  trunc(plr.len * sin(plr.phi/R2D));
  end;

var
  fn, p1_plr, p2_plr: polar;
  p1, p2: point;
begin
  setcolor(color);
  line(xs, ys, xf, yf);
  if xs <> xf then begin

    fn.phi := arctan((ys - yf) / (xf - xs)) * R2D;
    fn.len := sqrt(sqr(1.0*xf - xs) + sqr(1.0*yf - ys));

    p1_plr.phi := fn.phi + delta_phi; p1_plr.len := fn.len - delta_len;
    p2_plr.phi := fn.phi - delta_phi; p2_plr.len := fn.len - delta_len;

    polar_to_decart(p1_plr, p1);
    polar_to_decart(p2_plr, p2);

    line(p1.x, p1.y, xf, yf);
    line(p2.x, p2.y, xf, yf);
  end
  else begin
    line(xs - 2, yf - sign(yf - ys)*delta_len, xf, yf);
    line(xs + 2, yf - sign(yf - ys)*delta_len, xf, yf);
  end
end;

procedure ArrowLine(xs, ys, xf, yf: integer;
          positive: boolean; color:byte);
begin
  if positive then Arrow(xs, ys, xf, yf, color)
  else Arrow(xf, yf, xs, ys, color);
end;


var
  a, c: TGraph;
  i, j, v: Integer;
  gd, gm: Integer;
  k_sqrt: Integer;
  outstr_: String;
  coord: Array[1 .. nn] Of
    Record xc, yc: LongInt End;

Const
  x0 = 20; y0 = 20;
  size_: integer = 80;

begin
  ReadFileGraph( c );
  warshall(a,c);
  gd := Detect;

  InitGraph(gd, gm, '');
  k_sqrt := round(sqrt(n));

  i := 1; j := 1;
  For v := 1 To n Do Begin

    If (v <> main_n) and (a[v, main_n] = 10000)
      Then SetColor(Green) Else SetColor(Blue);

    If v = main_n Then SetColor(Red);

    Circle(x0+i*size_, y0+j*size_, 5);
    coord[v].xc := x0+i*size_; coord[v].yc := y0+j*size_;
    Str(v, outstr_);
    OutTextXY(x0+i*size_, y0+j*size_-10, outstr_);

    If i = k_sqrt Then Inc(j);

    If i < k_sqrt Then Inc(i) Else i := 1;
  End;

  For i := 1 To n Do
    For j := 1 To n Do Begin

      If (c[i,j] < 10000) and (i <> j) Then
        ArrowLine(coord[i].xc, coord[i].yc,
          coord[j].xc, coord[j].yc, True, White);
    End;

  ReadLn;
  CloseGraph;
end.