The famous City Central Zoo houses just two creatures,
Zebras and Ocelots. These magical creatures spend their time in
a single, tall column, each standing atop the back of the
creature below it. Whenever the zoo bell rings, the ocelot
lowest in the pile turns into a zebra, and all zebras (if there
are any) below that creature simultaneously turn into ocelots.
If there is no ocelot in the pile when the bell tolls, then
nothing happens. The zookeeper has been watching this
interesting process for years. Today, suddenly, he begins to
wonder how much longer this can go on. That is, given a pile of
zebras and/or ocelots, how many times may the bell toll before
there are no more ocelots?
Input
Input consists of a number $N$ in the range $1$ to $60$, followed by $N$ lines, each of which is a single
character, either Z (for zebra) or
O (for ocelot). These give the order of the
creatures from top (first) to bottom (last).
Output
Output should be a single integer giving the number of times
the bell must toll in order for there to be no more
ocelots.
Sample Input 1 
Sample Output 1 
3
Z
O
Z

2

Sample Input 2 
Sample Output 2 
4
O
Z
Z
O

9
