CF1108C.Nice Garland

You have a garland consisting of $n$ lamps. Each lamp is colored red, green or blue. The color of the $i$-th lamp is $s_i$ ('R', 'G' and 'B' — colors of lamps in the garland).

You have to recolor some lamps in this garland (recoloring a lamp means changing its initial color to another) in such a way that the obtained garland is nice.

A garland is called nice if any two lamps of the same color have distance divisible by three between them. I.e. if the obtained garland is $t$, then for each $i, j$ such that $t_i = t_j$ should be satisfied $|i-j|~ mod~ 3 = 0$. The value $|x|$ means absolute value of $x$, the operation $x~ mod~ y$ means remainder of $x$ when divided by $y$.

For example, the following garlands are nice: "RGBRGBRG", "GB", "R", "GRBGRBG", "BRGBRGB". The following garlands are not nice: "RR", "RGBG".

Among all ways to recolor the initial garland to make it nice you have to choose one with the minimum number of recolored lamps. If there are multiple optimal solutions, print any of them.

你有一条由 $n$ 盏灯组成的彩灯串。每盏灯的颜色为红色、绿色或蓝色。第 $i$ 盏灯的颜色为 $s_i$（其中 'R'、'G' 和 'B' 分别表示彩灯串中各灯的颜色）。

你需要重新给这条彩灯串中的某些灯染色（重染色指将某盏灯的初始颜色更改为另一种颜色），使得最终得到的彩灯串是“优美的”。

当且仅当任意两盏同色灯之间的距离能被 3 整除时，该彩灯串被称为“优美的”。即：若最终彩灯串为 $t$，则对所有满足 $t_i = t_j$ 的下标 $i, j$，都必须满足 $|i-j| \bmod 3 = 0$。其中 $|x|$ 表示 $x$ 的绝对值，$x \bmod y$ 表示 $x$ 除以 $y$ 的余数。

例如，以下彩灯串是优美的："RGBRGBRG"、"GB"、"R"、"GRBGRBG"、"BRGBRGB"；而以下彩灯串不是优美的："RR"、"RGBG"。

在所有能使初始彩灯串变为优美的重染色方案中，你需要选择重染灯数最少的一种。如果存在多种最优方案，输出任意一种即可。

The first line of the input contains one integer $n$ ($1 \le n \le 2 \cdot 10^5$) — the number of lamps.

The second line of the input contains the string $s$ consisting of $n$ characters 'R', 'G' and 'B' — colors of lamps in the garland.

输入的第一行包含一个整数 $n$（$1 \le n \le 2 \cdot 10^5$）—— 灯的数量。

输入的第二行包含一个长度为 $n$ 的字符串 $s$，由字符 'R'、'G' 和 'B' 组成 —— 表示彩灯串中各灯的颜色。

In the first line of the output print one integer $r$ — the minimum number of recolors needed to obtain a nice garland from the given one.

In the second line of the output print one string $t$ of length $n$ — a nice garland obtained from the initial one with minimum number of recolors. If there are multiple optimal solutions, print any of them.

在输出的第一行打印一个整数 $r$ —— 将给定的彩带变为“优美彩带”所需的最少重涂次数。

在输出的第二行打印一个长度为 $n$ 的字符串 $t$ —— 由初始彩带经过最少次数重涂后得到的一个“优美彩带”。若存在多个最优解，输出任意一个即可。