#include <bits/stdc++.h>
using namespace std;
int fun(string a, string b) {
  int cnt = 0;
  for (int i = 0; i < a.size(); i++) {
    if (a[i] != b[i]) cnt++;
  }
  return cnt;
}
int main() {
  int n;
  cin >> n;
  string s;
  cin >> s;
  vector<string> v1, v2;
  v1.push_back("BGR");
  v1.push_back("BRG");
  v1.push_back("RGB");
  v1.push_back("RBG");
  v1.push_back("GBR");
  v1.push_back("GRB");
  string temp;
  for (int i = 0; i < 6; i++) {
    string temp;
    for (int j = 0; j < n; j++) temp += v1[i][(j) % 3];
    v2.push_back(temp);
  }
  int ans = INT_MAX;
  string p;
  for (int i = 0; i < 6; i++) {
    int c = fun(v2[i], s);
    if (c < ans) {
      p = v2[i];
      ans = c;
    }
  }
  cout << ans << " " << p << endl;
}
