#include <bits/stdc++.h>   using namespace std;   template <class T>   inline void read(T &x) {     x = 0;     char c = getchar();     bool f = 0;     for (; !isdigit(c); c = getchar()) f ^= c ==  - ;     for (; isdigit(c); c = getchar()) x = (x << 3) + (x << 1) + (c ^ 48);     x = f ? -x : x;   }   int n, x, len, res, minn = 0x7fffffff;   char s[400001];   string ans, c[6] = { RGB ,  RBG ,  BRG ,  BGR ,  GRB ,  GBR };   int main() {     read(n);     scanf( %s , s), len = strlen(s);     for (int i = 0; i < 6; i++) {       res = 0, x = 0;       for (int j = 0; j < len; j++) {         if (s[j] != c[i][x++]) res++;         if (x == 3) x = 0;       }       if (res < minn) {         minn = res;         ans = c[i];       }     }     x = 0;     cout << minn <<   n ;     for (int j = 0; j < len; j++) {       putchar(ans[x++]);       if (x == 3) x = 0;     }     putchar(  n );     return 0;   }   