#include <bits/stdc++.h>
using namespace std;

#ifdef _RUTHEN
#include "debug.hpp"
#else
#define show(...) true
#endif

using ll = long long;
#define rep(i, n) for (int i = 0; i < (n); i++)
template <class T> using V = vector<T>;

int main() {
    ios::sync_with_stdio(false);
    cin.tie(0);
    V<string> S = {"C4", "D4", "E4", "F4", "G4", "A4", "B4"};
    V<double> H = {261.6, 294.3, 327.0, 348.8, 392.4, 436.0, 490.5};
    int N;
    cin >> N;
    V<int> A(N);
    rep(i, N) cin >> A[i];
    int d = 1 << 30, ansi = 0;
    rep(i, 7) {
        string s = S[i];
        double h = H[i];
        int M = h + 1;
        show(M);
        V<V<int>> G(M);
        rep(j, N) {
            int ind = h * j / N;
            G[ind].push_back(A[j]);
        }
        int m = min((int)G[0].size(), (int)G[1].size());
        int cd = 0;
        rep(j, m) cd += abs(G[0][j] - G[1][j]);
        if (d > cd) ansi = i, d = cd;
    }
    cout << S[ansi] << '\n';
    return 0;
}