Creating only one set of random values for every number slider update

Hi,

I was trying to create a slider controlled random distribution of points in a sketch. I wrote the code as shown below. Although it changes the number of random points when I update the slider value, it continuously produce new points and update position. I know it is happening because I kept the for loop inside the draw() function. How can I create only one collection of random point positions so that the points wont looks like they are flickering around .?

`import controlP5.*;
ControlP5 mycp5;

int number;

void setup() {

  size(600, 600);

  mycp5 = new ControlP5(this);

  mycp5.addSlider("number")
    .setPosition(300, 300)
    .setSize(100, 20)
    .setRange(0, 20)
    .setValue(1)
    ;
}

void draw() {

  background(250);

  for (int i =0; i<number; i++) {

    fill(200, 0, 0);
    ellipse(random(10, 200)+i*2, random(0, 200)+i*10, 10, 10);
  }
}
`