Three Boxes

Time limit2sMemory limit1024 MB

Summary

Given a string of L and R moves, simulate a ball moving among three boxes starting at box 1 (clamped at the ends) and count how many times it enters box 3.

Level: Easy1 of 10
Topics: Simulation, Implementation
Solved: No attempts yet

Problem

A string $S$ of length $N$ is given. Each character of $S$ is L or R.

There is one ball and three boxes that can hold the ball. The boxes are numbered 1, 2, and 3.

Initially, the ball is in box 1.

Beaver Bitaro performed $N$ operations on the boxes and the ball, starting from this state.

The $i$ -th operation ( $1 \le i \le N$ ) is performed as follows.

Let box $x$ $x$ be the box that contains the ball, and take the ball out of box $x$ $x$ . Then, depending on the $i$ $i$ -th character of $S$ $S$ , do one of the following.
- If the $i$ -th character of $S$ is L, put the ball into box $x-1$ . If $x$ is 1, put the ball into box 1.
- If the $i$ -th character of $S$ is R, put the ball into box $x+1$ . If $x$ is 3, put the ball into box 3.

Print the number of times the ball was put into box 3 over the $N$ operations.

Input

The input is given from Standard Input in the following format.

N
S

Output

Print the number of times the ball was put into box 3 over the $N$ operations.

Constraints

$1 \le N \le 100$ .
$S$ is a string of length $N$ .
Each character of $S$ is L or R.
$N$ is an integer.

Examples3

Example 1
Input
```
4
LRRR
```
Expected output
```
2
```
Example 2
Input
```
3
LRL
```
Expected output
```
0
```
Example 3
Input
```
7
LRLRRRL
```
Expected output
```
2
```