#include <bits/stdc++.h>
using namespace std;
template <typename Arg1>
void debug_out(const char* name, Arg1&& arg1) {
  cout << name << " = " << arg1 << " ]" << '\n';
}
template <typename Arg1, typename... Args>
void debug_out(const char* names, Arg1&& arg1, Args&&... args) {
  const char* comma = strchr(names + 1, ',');
  cout.write(names, comma - names) << " = " << arg1 << ",";
  debug_out(comma + 1, args...);
}
mt19937_64 rang(
    chrono::high_resolution_clock::now().time_since_epoch().count());
const long long mod = 1e9 + 7;
const long long N = 3e5, M = N;
void Solve_main() {
  long long n, m, k;
  string s;
  char won = '#';
  cin >> n >> s;
  deque<long long> d, r;
  for (long long i = (0); i < (n); ++i) {
    if (s[i] == 'D') {
      d.push_back(i);
    } else {
      r.push_back(i);
    }
  }
  while (!d.empty() && !r.empty()) {
    if (d.front() < r.front()) {
      r.pop_front();
      long long temp = d.front() + n;
      d.pop_front();
      d.push_back(temp);
    } else {
      d.pop_front();
      long long temp = r.front() + n;
      r.pop_front();
      r.push_back(temp);
    }
  }
  if (!d.empty()) {
    cout << 'D' << '\n';
  } else {
    cout << 'R' << '\n';
  }
}
int32_t main() {
  ios_base::sync_with_stdio(0), cin.tie(0), cout.tie(0);
  srand(chrono::high_resolution_clock::now().time_since_epoch().count());
  long long tc = 1;
  for (long long i = 0; i < tc; i++) {
    Solve_main();
  }
  cerr << "[time:" << 1.0 * clock() / CLOCKS_PER_SEC << "s] ";
  return 0;
}
