FEB

시간 제한2초메모리 제한1024 MB

요약

B, E, F로 이루어진 문자열에서 각 F를 B 또는 E로 바꿀 때 가능한 인접한 같은 문자 쌍 개수의 모든 값을 구한다.

난이도: 보통10점 중 7점
유형: 문자열, 그리디, 수학, 구현
정답자: 아직 제출이 없습니다

문제

Bessie and Elsie are plotting to overthrow Farmer John at last! They plan it out over $N$ ( $1\le N\le 2\cdot 10^5$ ) text messages. Their conversation can be represented by a string $S$ of length $N$ where $S\_i$ is either $B$ or $E$ , meaning the $i$ th message was sent by Bessie or Elsie, respectively.

However, Farmer John hears of the plan and attempts to intercept their conversation. Thus, some letters of $S$ are $F$ , meaning Farmer John obfuscated the message and the sender is unknown.

The excitement level of a non-obfuscated conversation is the number of times a cow double-sends - that is, the number of occurrences of substring $BB$ or $EE$ in $S$ . You want to find the excitement level of the original message, but you don’t know which of Farmer John’s messages were actually Bessie’s / Elsie’s. Over all possibilities, output all possible excitement levels of $S$ .

입력

The first line will consist of one integer $N$ .

The next line contains $S$ .

출력

First output $K$ , the number of distinct excitement levels possible. On the next $K$ lines, output the excitement levels, in increasing order.

예제3

예제 1
입력
```
4
BEEF
```
예상 출력
```
2
1
2
```
예제 2
입력
```
9
FEBFEBFEB
```
예상 출력
```
2
2
3
```
예제 3
입력
```
10
BFFFFFEBFE
```
예상 출력
```
3
2
4
6
```