## Counting Valleys

Gary is an avid hiker. He tracks his hikes meticulously, paying close attention to small details like topography. During his last hike, he took exactly steps. For every step he took, he noted if it was an *uphill* or a *downhill* step. Gary's hikes start and end at sea level. We define the following terms:

- A
*mountain*is a non-empty sequence of consecutive steps*above*sea level, starting with a step*up*from sea level and ending with a step*down*to sea level. - A
*valley*is a non-empty sequence of consecutive steps*below*sea level, starting with a step*down*from sea level and ending with a step*up*to sea level.

Given Gary's sequence of *up* and *down* steps during his last hike, find and print the number of *valleys* he walked through.

**Input Format**

The first line contains an integer, , denoting the number of steps in Gary's hike.

The second line contains a single string of characters. Each character is (where `U`

indicates a step *up* and `D`

indicates a step *down*), and the character in the string describes Gary's step during the hike.

**Constraints**

**Output Format**

Print a single integer denoting the number of valleys Gary walked through during his hike.

**Sample Input**

```
8
UDDDUDUU
```

**Sample Output**

```
1
```

**Explanation**

If we represent `_`

as sea level, a step up as `/`

, and a step down as `\`

, Gary's hike can be drawn as:

```
_/\ _
\ /
\/\/
```

It's clear that there is only one valley there, so we print on a new line.