#include <bits/stdc++.h>
using namespace std;
const int MAXN = 1e5 + 5;
int main() {
  int n;
  cin >> n;
  string s;
  cin >> s;
  queue<int> D, R;
  for (int i = 0; i < n; i++) {
    if (s[i] == 'D') D.push(i);
    if (s[i] == 'R') R.push(i);
  }
  while (D.size() && R.size()) {
    if (D.front() < R.front()) {
      R.pop();
      D.push(D.front() + n);
      D.pop();
    } else {
      D.pop();
      R.push(R.front() + n);
      R.pop();
    }
  }
  cout << (D.size() ? 'D' : 'R') << endl;
  return 0;
}
