Thanks Corinne for this riddle
We received one box containing 40 laces: 20 red and 20 grey.
We are in the darkness.
How many laces do we have to retire to be sure to have 2 of it of the same colour?
Congratulations Le roi fou on his solution of the 02/02/07 but don't look at it, it's always better to find oneself...
If you want to see the (false) solutions which were sent to me.