There are two kinds of books on a shelf: those on permissible magic and those on black magic. Two books on permissible magic cannot be set between exactly three other books, and two books on black magic may not stand next to each other. \par
What is the maximal amount of books that may be placed on the shelf?
16 rugby teams participate in a regional championship. Each pair of teams plays against each other twice. The 8 teams with the most wins will proceed to the national championship. If there is a tie in this ranking, the tied teams will draw lots. \par
Assume a rugby game can never tie. What is the minimum number of wins a team needs to guarantee a spot in the nationals?
}
\answer{23}
}
\problemdef{Misc}{5}{
\difficulty{5}
\statement{
Five boxes are filled with pastries. We know that box C contains a third of the pastries in E, and that B contains two times more than C and E combined. A contains half the number of pastries in E, and a tenth of those in D. Box B contains four times more pastries than D. \par
What is the minimal possible positive number of pastries in all the boxes put together?