#include <bits/stdc++.h>
using namespace std;
//*
#include <atcoder/all>
using namespace atcoder;
using mint = modint998244353;
//using mint = modint1000000007;
//*/
using ll = long long;
using ld = long double;
using pll = pair<ll, ll>;
using tlll = tuple<ll, ll, ll>;
constexpr ll INF = 1LL << 60;
template<class T> bool chmin(T& a, T b) {if (a > b) {a = b; return true;} return false;}
template<class T> bool chmax(T& a, T b) {if (a < b) {a = b; return true;} return false;}
ll safemod(ll A, ll M) {return (A % M + M) % M;}
ll divfloor(ll A, ll B) {if (B < 0) {return divfloor(-A, -B);} return (A - safemod(A, B)) / B;}
ll divceil(ll A, ll B) {if (B < 0) {return divceil(-A, -B);} return divfloor(A + B - 1, B);}
template<class T> void unique(vector<T> &V) {V.erase(unique(V.begin(), V.end()), V.end());}
template<class T> void sortunique(vector<T> &V) {sort(V.begin(), V.end()); V.erase(unique(V.begin(), V.end()), V.end());}
#define FINALANS(A) do {cout << (A) << '\n'; exit(0);} while (false)
template<class T> void printvec(const vector<T> &V) {int _n = V.size(); for (int i = 0; i < _n; i++) cout << V[i] << (i == _n - 1 ? "" : " ");cout << '\n';}
template<class T> void printvect(const vector<T> &V) {for (auto v : V) cout << v << '\n';}
template<class T> void printvec2(const vector<vector<T>> &V) {for (auto &v : V) printvec(v);}

vector<ll> shift(vector<ll> &A, ll k)
{
  ll N = A.size();
  vector<ll> res(N);
  for (ll i = 0; i < N; i++)
  {
    res.at(i) = A.at(i);
  }

  res.erase(res.begin(), res.begin() + k);
  return res;
}

ll f(const vector<ll> &A, const vector<ll> &B)
{
  ll N = min(A.size(), B.size());
  ll ans = 0;
  for (ll i = 0; i < N; i++)
  {
    ans += abs(A.at(i) - B.at(i));
  }
  return ans;
}

int main()
{
  ll N;
  cin >> N;
  vector<ll> A(N);
  for (ll i = 0; i < N; i++)
  {
    cin >> A.at(i);
  }

  const vector<ld> lambdas = {261.6, 294.3, 327.0, 348.8, 392.4, 436.0, 490.5};
  ll ans = -1, mn = INF;
  for (ll i = 0; i < 7; i++)
  {
    ll k0 = N / lambdas.at(i);
    for (ll k = k0 - 5; k <= k0 + 5; k++)
    {
      ll tmp = f(A, shift(A, k));
      if (chmin(mn, tmp))
        ans = i;
    }
  }
  cout << "CDEFGAB"[ans] << 4 << endl;
}