Package for this problem was not updated by the problem writer or Codeforces administration after we’ve upgraded the judging servers. To adjust the time limit constraint, solution execution time will be multiplied by 2. For example, if your solution works for 400 ms on judging servers, then value 800 ms will be displayed and used to determine the verdict.

Virtual contest is a way to take part in past contest, as close as possible to participation on time. It is supported only ICPC mode for virtual contests.
If you've seen these problems, a virtual contest is not for you - solve these problems in the archive.
If you just want to solve some problem from a contest, a virtual contest is not for you - solve this problem in the archive.
Never use someone else's code, read the tutorials or communicate with other person during a virtual contest.

No tag edit access

C. Hamsters and Tigers

time limit per test

2 secondsmemory limit per test

256 megabytesinput

standard inputoutput

standard outputToday there is going to be an unusual performance at the circus — hamsters and tigers will perform together! All of them stand in circle along the arena edge and now the trainer faces a difficult task: he wants to swap the animals' positions so that all the hamsters stood together and all the tigers also stood together. The trainer swaps the animals in pairs not to create a mess. He orders two animals to step out of the circle and swap places. As hamsters feel highly uncomfortable when tigers are nearby as well as tigers get nervous when there's so much potential prey around (consisting not only of hamsters but also of yummier spectators), the trainer wants to spend as little time as possible moving the animals, i.e. he wants to achieve it with the minimal number of swaps. Your task is to help him.

Input

The first line contains number *n* (2 ≤ *n* ≤ 1000) which indicates the total number of animals in the arena. The second line contains the description of the animals' positions. The line consists of *n* symbols "H" and "T". The "H"s correspond to hamsters and the "T"s correspond to tigers. It is guaranteed that at least one hamster and one tiger are present on the arena. The animals are given in the order in which they are located circle-wise, in addition, the last animal stands near the first one.

Output

Print the single number which is the minimal number of swaps that let the trainer to achieve his goal.

Examples

Input

3

HTH

Output

0

Input

9

HTHTHTHHT

Output

2

Note

In the first example we shouldn't move anybody because the animals of each species already stand apart from the other species. In the second example you may swap, for example, the tiger in position 2 with the hamster in position 5 and then — the tiger in position 9 with the hamster in position 7.

Codeforces (c) Copyright 2010-2019 Mike Mirzayanov

The only programming contests Web 2.0 platform

Server time: Dec/15/2019 14:54:53 (h3).

Desktop version, switch to mobile version.

Supported by

User lists

Name |
---|