Alicia In Thw Wonderland

Alicia was wandering around the forest when she heard the starnge voices.

She was a very curious girl so she climbed the nearby tree and witnessed a strange meeting.

There was a huge round table with 31 people sitting aroung it.

In front of the table stood the Great Wizard. He has quieted the members of the gathering and said:

My dear friends, we are here on our 125th annual meeting.

We will listen to different interesting stories, which ordinary people can not understand. But before we start we have to make sure that there is no intruder among us.

After that the Great Wizard started to walk around the table putting a color dot (a sticker) on a forehead of each wizard.

After he has finished he came back to the front of the table and started to explain his experiment.

You can see the dots on the foreheads of other members but you can't see your own dot. You have to find out the color of your dot.

There is only one rule and it's simple. Each minute the bell will ring. If you know the color of your dot please stand up and go to the field on the hill where we will continue our meeting. But if you do not know it, stay at your table.

One who will stay at his table when was supposed to stand up, or will stand up when was supposed to sit can not call himself a magician and will be removed from the meeting.

The Great Wizard was about to leave when he notice the orried face of one of the most inteligent novice. So the Great Wizard said to him:

Do not worry young boy, it is possible to solve this, but of course you can't talk to each other.

The novice smiled as he knew that the Great Wizard is never wrong and never uses false statements.

Then The Great Wizard left the gathering and went to the nearby hill and the experiment started.

The first bellring: 4 people leave the table;

The second ring: all people with red dots stood up and left;

The third ring: Nobody moved;

The fourth ring: at least one person stood up and left;

The novice and his sister, also present at the meeting, both with different colors stood up a few moments after but before the last ring.

Alicia was however very tired by now and she felt asleep.

Can you tell how how many times the bell rang before everybody left?