Ошибка в рисовании окружностей

program okruzhnost;
var x1,x2,y2,y1,i,N,hc, c :integer;
x,h,y,yy,xx,hy,a :real;
begin
x1:=100; y1:=100;
x2:=300; y2:=300;
writeln ('Введите число окружностей ');
read (N);
h:=(x2-x1)/(N+1);
hy:=(y2-y1)/(N+1);
ellipse (x1,y1,x2,y2);
x:=x1+h; y:=y1+hy;
xx:=x2-h; yy:=y2-hy;
c:=0; hc:=255 div N;
for i:=1 to N do begin
ellipse (round (x), round(y), round (xx), round (yy));
x:=x+h; y:=y+hy;
xx:=xx-h; yy:=yy-hy;
end;
end.

program okruzhnost;
uses graphABC,crt;
var r1,r2,x,y,i,N,c :integer;
    h:real;
begin
randomize;
r1:=50;
r2:=150;
x:=windowwidth div 2;
y:=windowheight div 2;
writeln ('Введите число окружностей ');
readln (N);
h:=(r2-r1)/(N+1);
setbrushstyle(bsClear);
for i:=1 to N do
 begin
  setpencolor(clrandom);
  circle(x,y,r1+round(h*(i-1)));
 end;
end.

var x1,x2,y2,y1,i,N :integer;
    h,hy :real;
begin
randomize;
x1:=100; y1:=100;
x2:=300; y2:=300;
writeln ('Ââåäèòå ÷èñëî îêðóæíîñòåé ');
readln (N);
h:=(x2-x1)/(N+1)/2;{íóæíî åùå ïîäåëèòü íà 2}
hy:=(y2-y1)/(N+1)/2;
for i:=1 to n do
 begin
  pen(1,random(255),random(255),random(255));
  ellipse(x1+round((i-1)*h),y1+round((i-1)*hy),x2-round((i-1)*h),y2-round((i-1)*hy));
 end; 
end.