// cos で畳み込んでいるため WA
#include <cmath>
#include <iostream>
#include <string>
#include <vector>
using namespace std;

const vector<double> freqs{261.6, 294.3, 327.0, 348.8, 392.4, 436.0, 490.5};
const vector<string> names{"C4", "D4", "E4", "F4", "G4", "A4", "B4"};

int main() {
    cin.tie(nullptr), ios::sync_with_stdio(false);
    int N;
    cin >> N;
    vector<double> A(N);
    for (auto &x : A) cin >> x;

    const double PI = acos(-1);
    double high = -1;
    int arghi = -1;

    for (int d = 0; d < int(freqs.size()); ++d) {
        double v = 0;
        for (int frame = 0; frame < N; ++frame) {
            v += cos(PI * 2 * frame / N * freqs[d]) * A[frame];
        }
        if (high < abs(v)) {
            high = abs(v);
            arghi = d;
        }
    }
    cout << names.at(arghi) << '\n';
}