#include <bits/stdc++.h>

std::array<double, 7> const freqs = {261.6, 294.3, 327.0, 348.8, 392.4, 436.0, 490.5};

int main() {
  int N;
  std::cin >> N;
  std::vector<int> A(N);
  for (int& e : A) { std::cin >> e; }

  std::vector<int> suff(N + 1);
  for (int i = N; i--;) { suff[i] = A[i] + suff[i + 1]; }

  int mn = std::numeric_limits<int>::max();
  int ans = -1;
  for (int t = 0; t < 7; ++t) {
    int w = int(std::round(N / freqs[t]));
    int mx = 0;
    for (int i = 0; i + w <= N; ++i) { mx = std::max(mx, std::abs(suff[i] - suff[i + w])); }
    if (mx < mn) {
      mn = mx;
      ans = t;
    }
  }
  std::cout << "CDEFGAB"[ans] << "4\n";
}