Language: C++

/*input

*/
#include<bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace std;
using namespace __gnu_pbds;

#define int long long 
#define double long double
#define f first
#define s second
#define mp make_pair
#define pb push_back

#define RE(i,n) for (int i = 1; i <= n; i++)
#define RED(i,n) for (int i = n; i > 0; i--)
#define REPS(i,n) for(int i = 1; (i*i) <= n; i++)
#define REP(i,n) for (int i = 0; i < (int)n; i++)
#define FOR(i,a,b) for (int i = a; i < b; i++)
#define REPD(i,n) for (int i = n-1; i >= 0; i--)
#define FORD(i,a,b) for (int i = a; i >= b; i--)

#define all(v) v.begin(),v.end()
#define pii pair<int,int>
#define vi vector<int>
#define vvi vector<vi>
#define print(arr) for (auto it = arr.begin(); it != arr.end(); ++it) cout << *it << " "; cout << endl;
#define debug(x) cout << x << endl;
#define debug2(x,y) cout << x << " " << y << endl;
#define debug3(x,y,z) cout << x << " " << y << " " << z << endl;

typedef tree<
int,
null_type,
less<int>,
rb_tree_tag,
tree_order_statistics_node_update>
ordered_set;

const int INF = 1e18+1;
const int MOD = 1e9+7;
const double PI = 3.14159265358979323846264338;

int raise(int a,int n,int m = MOD){
  if(n == 0)return 1;
  if(n == 1)return a;
  int x = 1;
    x *= raise(a,n/2,m);
    x %= m;
    x *= x;
    x %= m;
    if(n%2)x*= a;
    x %= m;
    return x;
}

int floor1(int n,int k){
    if(n%k == 0 || n >= 0)return n/k;
    return (n/k)-1;
}

int ceil1(int n,int k){
    return floor1(n+k-1,k);
}

const int N = 99;
vector<int> order;
mt19937 rng((int) std::chrono::steady_clock::now().time_since_epoch().count());
int ans[N];
int n;

bool query(int i){
	cout << "? ";
	for(int k = i;k < i+n;k++)cout << order[k] << " ";
	cout << endl;
	string x;cin >> x
	return (x == 'Red');
}

vector<int> crucial;
vector<int> nsg;

bool find(int i){
	cout << "? " << order[i] << " ";
	print(crucial);
	string x;cin >> x
	return (x == 'Red');
}

bool find1(int i){
	cout << "? " << order[i] << " ";
	print(nsg);
	string x;cin >> x
	return (x == 'Red');
}

int eh[2*N];

void solve(){
  	cin >> n;
  	RE(i,2*n){
  		order.pb(i-1);
  	}
  	shuffle(all(order),rng);
  	bool lst = query(0);
  	RE(i,n){
  		bool nw = query(i);
  		if(nw == lst){
  			lst = nw;
  			continue;
  		}
  		ans[order[i+n-1]] = nw;
  		ans[order[i-1]] = lst;
  		for(int k = i;k < i+n-1;k++){
  			crucial.pb(order[k]);
  			eh[k] = 1;
  		}
  		for(int k = 0;k < 2*n;k++){
  			if(k < i-1 or k > i+n-1){
  				nsg.pb(order[k]);
  				eh[k] = 2;
  			}
  		}
  		break;
  	}
  	REP(i,2*n){
  		if(!eh[i])continue;
  		if(eh[i] == 2){
  			ans[order[i]] = find(i);
  		}
  		else{
  			ans[order[i]] = find1(i);
  		}
  	}	
  	cout << "! ";
  	REP(i,2*n){
  		if(ans[i])cout << "R";
  		else cout << "B";
  	}
  	cout << endl;
}

signed main(){
  ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);
  //freopen(".in","r",stdin);freopen(".out","w",stdout);
  int t = 1;
  //cin >> t;
  while(t--){
    solve();
  }
  return 0;
}

Compiler output:
a.cc:79:22: warning: multi-character character constant [-Wmultichar]
   79 |         return (x == 'Red');
      |                      ^~~~~
a.cc:89:22: warning: multi-character character constant [-Wmultichar]
   89 |         return (x == 'Red');
      |                      ^~~~~
a.cc:96:22: warning: multi-character character constant [-Wmultichar]
   96 |         return (x == 'Red');
      |                      ^~~~~
a.cc: In function 'bool query(long long int)':
a.cc:78:26: error: expected ';' before 'return'
   78 |         string x;cin >> x
      |                          ^
      |                          ;
   79 |         return (x == 'Red');
      |         ~~~~~~            
a.cc:80:1: warning: no return statement in function returning non-void [-Wreturn-type]
   80 | }
      | ^
a.cc: In function 'bool find(long long int)':
a.cc:88:26: error: expected ';' before 'return'
   88 |         string x;cin >> x
      |                          ^
      |                          ;
   89 |         return (x == 'Red');
      |         ~~~~~~            
a.cc:90:1: warning: no return statement in function returning non-void [-Wreturn-type]
   90 | }
      | ^
a.cc: In function 'bool find1(long long int)':
a.cc:95:26: error: expected ';' before 'return'
   95 |         string x;cin >> x
      |                          ^
      |                          ;
   96 |         return (x == 'Red');
      |         ~~~~~~            
a.cc:97:1: warning: no return statement in function returning non-void [-Wreturn-type]
   97 | }
      | ^