#include <iostream>
#include <vector>
#include <algorithm>
#include <cmath>
#include <atcoder/modint>
using namespace std;
using i32 = int;
using u32 = unsigned int;
using i64 = long long;
using u64 = unsigned long long;
#define rep(i,n) for(int i=0; i<(int)(n); i++)

using m32 = atcoder::modint998244353;

int main(){
    int N; cin >> N;
    vector<double> A(N);
    rep(i,N){ int a; cin >> a; A[i] = a; }
    vector<pair<double, string>> tones = {
        { 261.6 , "C4" },
        { 294.3 , "D4" },
        { 327.0 , "E4" },
        { 348.8 , "F4" },
        { 392.4 , "G4" },
        { 436.0 , "A4" },
        { 490.5 , "B4" }
    };
    auto f = [&](double p) -> double {
        double l = A[floor(p)];
        double r = A[ceil(p)];
        double x = p - floor(p);
        return l + (r-l) * x;
    };

    pair<double, int> ans = { 1e100, 0 };
    rep(ty,tones.size()){
        double dt = 44100.0 / tones[ty].first;
        double diff = 0;
        for(int i=0; i<N-300; i++){
            double dy = abs(A[i] - f(i+dt));
            diff += dy * dy;
        }
        ans = min(ans, make_pair(diff, ty));
    }

    cout << tones[ans.second].second << endl;
    return 0;
}

struct ios_do_not_sync{
    ios_do_not_sync(){
        std::ios::sync_with_stdio(false);
        std::cin.tie(nullptr);
    }
} ios_do_not_sync_instance;