CF1082B Vova and Trophies

你现在有 $n$ 枚奖牌，每枚奖牌为金牌或银牌。这些奖牌现在按顺序排成一排。现在你可以调换任意一对奖牌的位置，求金牌最长连续段。

第一行一个整数 $n$ $(2\le n\le 10^5)$ . 第二行一行字符串，表示你的奖牌。 ( $\texttt{G}$ 表示金牌，$\texttt{S}$ 表示银牌)

输出一个整数表示答案。

In the first example Vova has to swap trophies with indices $ 4 $ and $ 10 $ . Thus he will obtain the sequence "GGGGGGGSGS", the length of the longest subsegment of golden trophies is $ 7 $ . In the second example Vova can make no swaps at all. The length of the longest subsegment of golden trophies in the sequence is $ 4 $ . In the third example Vova cannot do anything to make the length of the longest subsegment of golden trophies in the sequence greater than $ 0 $ .