#include <bits/stdc++.h>   const double eps = (1e-9);   using namespace std;   int dcmp(long double a, long double b) {     return fabsl(a - b) <= eps ? 0 : (a > b) ? 1 : -1;   }   int getBit(long long num, int idx) { return ((num >> idx) & 1ll) == 1; }   int setBit1(int num, int idx) { return num | (1 << idx); }   long long setBit0(long long num, int idx) { return num & ~(1ll << idx); }   long long flipBit(long long num, int idx) { return num ^ (1ll << idx); }   void M() {     ios_base::sync_with_stdio(0);     cin.tie(0);     cout.tie(0);   }   int countNumBit1(int mask) {     int ret = 0;     while (mask) {       mask &= (mask - 1);       ++ret;     }     return ret;   }   string st;   int n;   int main() {     M();     cin >> n >> st;     char c1, c2, c3, F, S, T;     int mi = INT_MAX;     for (int i = 1; i <= 3; i++) {       for (int j = 1; j <= 3; j++) {         for (int k = 1; k <= 3; k++) {           int cnt1 = 0, cnt2 = 0, cnt3 = 0;           if (i == j || i == k || j == k) continue;           c1 = (i == 1 ?  R  : (i == 2 ?  B  :  G ));           c2 = (j == 1 ?  R  : (j == 2 ?  B  :  G ));           c3 = (k == 1 ?  R  : (k == 2 ?  B  :  G ));           for (int l = 0; l < n; l += 3) {             if (st[l] != c1) cnt1++;           }           for (int l = 1; l < n; l += 3) {             if (st[l] != c2) cnt2++;           }           for (int l = 2; l < n; l += 3) {             if (st[l] != c3) cnt3++;           }           long long ans = cnt1 + cnt2 + cnt3;           if (ans < mi) {             mi = ans;             F = c1;             S = c2;             T = c3;           }         }       }     }     for (int l = 0; l < n; l += 3) {       st[l] = F;     }     for (int l = 1; l < n; l += 3) {       st[l] = S;     }     for (int l = 2; l < n; l += 3) {       st[l] = T;     }     cout << mi << endl << st << endl;   }   