Donald Duck works as a postman for the Walt Disney Studios.
He delivers children’s letters from all over the world to his friends,
which are cartoon characters. The Studios has three cases for the letters,
with nine sections in each case. Every section has the name of
the receiver on it. All cases stand in a row as it is shown at the picture
Donald Duck have brought n letters today. Initially, he stands near
the leftmost case. He has to make one step to go to the neighboring case or to the previous one.
How many steps will he make until he puts all the letters into
the respective sections, if he does this in the order they are in his bag?
The first line contains an integer n that is the amount of letters
in Donald’s bag (1 ≤ n ≤ 1 000). The following n lines contain
receivers of the letters in the order they are in the bag.
Output the number of steps Donald should make to put all the letters into the cases.
Problem Author: Alex Samsonov
Problem Source: NEERC 2014, Eastern subregional contest