#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using ld = long double;
using V = vector<int>;
using Vll = vector<ll>;
using Vld = vector<ld>;
using Vbo = vector<bool>;
using VV = vector<V>;
using VVll = vector<Vll>;
using VVld = vector<Vld>;
using VVbo = vector<Vbo>;
using VVV = vector<VV>;
using VVVll = vector<VVll>;
using P = pair<int, int>;
using Pll = pair<ll, ll>;
using Pld = pair<ld, ld>;
#define rep2(i, m, n) for (int i = (m); i < (n); ++i)
#define drep2(i, m, n) for (int i = (m)-1; i >= (n); --i)
#define rep(i, n) rep2(i, 0, n)
#define drep(i, n) drep2(i, n, 0)
#define all(a) (a).begin(), (a).end()
// struct fast_ios { fast_ios(){ cin.tie(nullptr); ios::sync_with_stdio(false); cout << fixed << setprecision(20); }; } fast_ios_;
template<typename T> inline int sz(T &x) { return x.size(); }
template<typename T> inline bool chmin(T &a, T b) { if (a > b) { a = b; return true; } return false; }
template<typename T> inline bool chmax(T &a, T b) { if (a < b) { a = b; return true; } return false; }
template<typename T1, typename T2> istream &operator>>(istream &is, pair<T1, T2> &p) { is >> p.first >> p.second; return is; }
template<typename T1, typename T2> ostream &operator<<(ostream &os, const pair<T1, T2> &p) { os << '(' << p.first << ", " << p.second << ')'; return os; }
template<typename T> istream &operator>>(istream &is, vector<T> &v) { for (auto &e : v) is >> e; return is; }
template<typename T> ostream &operator<<(ostream &os, const vector<T> &v) { for (auto &e : v) os << e << ' '; return os; }
template<typename T> inline int count_between(vector<T> &a, T l, T r) { return lower_bound(all(a), r) - lower_bound(all(a), l); } // [l, r)
inline int fLog2(const int x) { assert(x > 0); return 31-__builtin_clz(x); } // floor(log2(x))
inline int fLog2(const ll x) { assert(x > 0); return 63-__builtin_clzll(x); }
inline int cLog2(const int x) { assert(x > 0); return (x == 1) ? 0 : 32-__builtin_clz(x-1); } // ceil(log2(x))
inline int cLog2(const ll x) { assert(x > 0); return (x == 1) ? 0 : 64-__builtin_clzll(x-1); }
inline int popcount(const int x) { return __builtin_popcount(x); }
inline int popcount(const ll x) { return __builtin_popcountll(x); }
void fail() { cout << -1 << '\n'; exit(0); }
// const int INF  = 1<<30;
// const ll INFll = 1ll<<62;
// const ld EPS   = 1e-10;
// const ld PI    = acos(-1.0);
// const int MOD  = int(1e9)+7;
// const int MOD  = 998244353;


V rng(int l, int r) {
  int n = r - l + 1;
  V res(n);
  rep(i, n) res[i] = l + i;
  return res;
}


int main() {
  int n; cin >> n;

  auto f = [&] (int i) {
    cout << "? " << rng(i, i+n-1) << endl;
    string s; cin >> s;
    assert(s != "-1");
    if (s == "Red") return 0;
    else return 1;
  };

  int l = 1;
  int r = n+1;
  int xl = f(l);
  int xr = xl^1;

  while (r - l > 1) {
    int m = (l + r) >> 1;
    int xm = f(m);
    if (xl == xm) l = m;
    else r = m;
  }
  
  V ans(2*n+1, -1);
  ans[l] = xl;
  ans[l+n] = xr;

  rep2(i, 1, 2*n+1) {
    if (i == l || i == l+n) continue;
    if (i < l || n+l < i) cout << "? " << rng(l+1, l+n-1) << i << endl;
    else cout << "? " << rng(1, l-1) << rng(l+n+1, 2*n) << i << endl;
    string s; cin >> s;
    assert(s != "-1");
    int y = (s == "Red" ? 0 : 1);
    ans[i] = y;
  }

  cout << "! ";
  rep2(i, 1, 2*n+1) cout << (ans[i] == 0 ? 'R' : 'B');
  cout << endl;
  return 0;
}


Measured memory_bytes: 3792