program Decharge_electrique;
uses crt,graph;

const c=180/pi;
      dl=3;
      eps=5;

Function Atn(x:real):real;
Var ordre:integer; S,c:real;
Begin
  ordre:=21; {Imp‚rativement impair}
  c:=x*x;
  S:=1/ordre;
  While ordre>1 do Begin
    ordre:=ordre-2;
    S:=-c*S+1/ordre;
  end;
  Atn:=x*S;
end;

Function Arctan(x:real):real;
Var y:real;
begin
  If abs(x)<1 then arctan:=atn(x)
    else if x>0 then begin
      y:=(x-1)/(x+1);
      Arctan:=pi/4+Atn(y);
    end
      else begin
        y:=(-x-1)/(-x+1);
        Arctan:=-pi/4-Atn(y);
      end;
end;

Function Puissance(x:real;n:integer):real;
Begin
  If n=0 then Puissance:=1
    else if odd(n) then Puissance:=x*Puissance(x,n-1)
      else Puissance:=sqr(Puissance(x,n div 2));
end;

var ch:char;
     x1,y1,x2,y2,x,y,gd,gm,x01,x02,y01,y02:integer;
     distance,angle:real;
begin
  gd:=detect;
  initgraph(gd,gm,'c');

  randomize;
  x01:=5+random(50);y01:=random(479);
  x02:=639-x01;y02:=random(479);
  line(x01,y01,x01,y01);line(x02,y02,x02,y02);
  while not (ch='s') do begin
   x1:=x01;y1:=y01;
   x2:=x02;y2:=y02;
   randomize;
   distance:=sqrt(abs(x2-x1)+abs(y2-y1));
   while distance>eps do
     begin
       if x1=x2 then exit;
       angle:=round(arctan((y2-y1)/(x2-x1))*c)+random(220)-90;
       x:=x1+round(dl*cos(angle/c));
       y:=y1+round(dl*sin(angle/c));
       line(x1,y1,x,y);
       x1:=x;
       y1:=y;
       distance:=sqrt(abs(x2-x1)+abs(y2-y1));
     end;
   ch:=readkey;
  end;

  closegraph;
end.