Marisa's vibrant mushroom garden consists of $n$ mushrooms of three types: red, green, and yellow. Marisa thinks that two mushrooms of the same color next to each other do not look good, so she decides to swap the mushrooms using the operation of choosing two adjacent mushrooms and swapping them. Help Marisa calculate the minimum number of swaps required so that no two mushrooms of the same color are adjacent.
### Input
- The first line contains an integer $n$.
- The second line contains a string of $n$ characters consisting of the letters `R`, `G`, and `Y`, representing red, green, and yellow respectively.
### Output
- Print the minimum number of swaps required. Print `-1` if it is not possible to rearrange them in the desired way.
### Constraints
- $1 \le n \le 400$.
### Example
Input:
```
4
RRGY
```
Output:
```
1
```
Input 2:
```
5
YYYYY
```
Output 2:
```
-1
```
Input 3:
```
8
RRGGYRYY
```
Output 3:
```
3
```
### Subtasks
- $5\\%$ of the test cases have $n \le 15$.
- $55\\%$ of the test cases have $n \le 60$.
- $15\\%$ of the test cases consist of strings with only the characters `R` and `G`.
- The remaining test cases have no additional constraints.
