#include <bits/stdc++.h>   using namespace std;   const int N = 111;   int a[N], b[N];   int main() {     cin.tie(0)->sync_with_stdio(0);     int t;     cin >> t;     while (t--) {       queue<int> que;       int n;       cin >> n;       string S;       cin >> S;       S =     + S;       for (int i = 1; i <= n; i++) {         if (S[i] ==  R ) {           a[i] = 1;           b[i] = 1;           que.push(i);         } else if (S[i] ==  B ) {           a[i] = 2;           b[i] = 2;           que.push(i);         } else {           a[i] = 3;           b[i] = 3;         }       }       if (que.empty()) {         for (int i = 1; i <= n; i++) {           if (i % 2 == 1)             cout <<  R ;           else             cout <<  B ;         }         cout <<   n ;         continue;       }       while (!que.empty()) {         int x = que.front();         que.pop();         int left = x - 1;         int right = x + 1;         while (b[left] == 3 && left >= 1) {           if (b[left + 1] == 1) {             b[left] = 2;             left--;           } else {             b[left] = 1;             left--;           }         }         while (b[right] == 3 && right <= n) {           if (b[right - 1] == 1) {             b[right] = 2;             right++;           } else {             b[right] = 1;             right++;           }         }       }       for (int i = 1; i <= n; i++) {         if (b[i] == 1)           cout <<  R ;         else           cout <<  B ;       }       cout <<   n ;     }     return 0;   }   